drm/i915: Introduce IS_GEN9_BC for Skylake and Kabylake.

Along with GLK it was introduced the .is_lp and IS_GEN9_LP.
So, following the same simplification standard we can
put Skylake and Kabylake under the same bucket for most
of the things.

So let's add the IS_GEN9_BC for "Big Core" (non Atom based
platforms).

The i915_drv.c was let out of this patch on purpose
because that is really a decision per platform, just like
other cases where IS_KABYLAKE is different from IS_SKYLAKE.

v2: fix conflict with IS_LP and 3 new cases for this
    big core bucket:
    - intel_ddi.c: intel_ddi_get_link_dpll
    - intel_fbc.c: find_compression_threshold
    - i915_gem_gtt.c: gtt_write_workarounds

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1485196357-30599-2-git-send-email-rodrigo.vivi@intel.com
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5f55bc3..5a9da48 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5800,7 +5800,7 @@ static int skl_calc_cdclk(int max_pixclk, int vco);
 
 static void intel_update_max_cdclk(struct drm_i915_private *dev_priv)
 {
-	if (IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv)) {
+	if (IS_GEN9_BC(dev_priv)) {
 		u32 limit = I915_READ(SKL_DFSM) & SKL_DFSM_CDCLK_LIMIT_MASK;
 		int max_cdclk, vco;
 
@@ -10673,7 +10673,7 @@ static void haswell_get_ddi_port_state(struct intel_crtc *crtc,
 
 	port = (tmp & TRANS_DDI_PORT_MASK) >> TRANS_DDI_PORT_SHIFT;
 
-	if (IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv))
+	if (IS_GEN9_BC(dev_priv))
 		skylake_get_ddi_pll(dev_priv, port, pipe_config);
 	else if (IS_GEN9_LP(dev_priv))
 		bxt_get_ddi_pll(dev_priv, port, pipe_config);
@@ -15681,7 +15681,7 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
 		 */
 		found = I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_INIT_DISPLAY_DETECTED;
 		/* WaIgnoreDDIAStrap: skl */
-		if (found || IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv))
+		if (found || IS_GEN9_BC(dev_priv))
 			intel_ddi_init(dev_priv, PORT_A);
 
 		/* DDI B, C and D detection is indicated by the SFUSE_STRAP
@@ -15697,7 +15697,7 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
 		/*
 		 * On SKL we don't have a way to detect DDI-E so we rely on VBT.
 		 */
-		if ((IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv)) &&
+		if (IS_GEN9_BC(dev_priv) &&
 		    (dev_priv->vbt.ddi_port_info[PORT_E].supports_dp ||
 		     dev_priv->vbt.ddi_port_info[PORT_E].supports_dvi ||
 		     dev_priv->vbt.ddi_port_info[PORT_E].supports_hdmi))
@@ -16196,7 +16196,7 @@ void intel_init_display_hooks(struct drm_i915_private *dev_priv)
 	}
 
 	/* Returns the core display clock speed */
-	if (IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv))
+	if (IS_GEN9_BC(dev_priv))
 		dev_priv->display.get_display_clock_speed =
 			skylake_get_display_clock_speed;
 	else if (IS_GEN9_LP(dev_priv))
@@ -16277,7 +16277,7 @@ void intel_init_display_hooks(struct drm_i915_private *dev_priv)
 			bxt_modeset_commit_cdclk;
 		dev_priv->display.modeset_calc_cdclk =
 			bxt_modeset_calc_cdclk;
-	} else if (IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv)) {
+	} else if (IS_GEN9_BC(dev_priv)) {
 		dev_priv->display.modeset_commit_cdclk =
 			skl_modeset_commit_cdclk;
 		dev_priv->display.modeset_calc_cdclk =