drm/i915: Make SKL/KBL DPLL0 managed by the shared dpll code

Include DPLL0 in the managed dplls for SKL/KBL. While it has to be kept
enabled because of it driving CDCLK, it is better to special case that
inside the DPLL code than in the higher level.

v2: Use INTEL_DPLL_ALWAYS_ON flag. (Ander)

v3: Remove extremely paranoid WARN_ONs. (Maarten)
    Handle DPLL0 in skylake_get_ddi_pll() properly. (Ander)

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457451987-17466-14-git-send-email-ander.conselvan.de.oliveira@intel.com
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7e00ee5..28556a8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9771,21 +9771,15 @@
 				struct intel_crtc_state *pipe_config)
 {
 	enum intel_dpll_id id;
-	u32 temp, dpll_ctl1;
+	u32 temp;
 
 	temp = I915_READ(DPLL_CTRL2) & DPLL_CTRL2_DDI_CLK_SEL_MASK(port);
 	pipe_config->ddi_pll_sel = temp >> (port * 3 + 1);
 
 	switch (pipe_config->ddi_pll_sel) {
 	case SKL_DPLL0:
-		/*
-		 * On SKL the eDP DPLL (DPLL0 as we don't use SSC) is not part
-		 * of the shared DPLL framework and thus needs to be read out
-		 * separately
-		 */
-		dpll_ctl1 = I915_READ(DPLL_CTRL1);
-		pipe_config->dpll_hw_state.ctrl1 = dpll_ctl1 & 0x3f;
-		return;
+		id = DPLL_ID_SKL_DPLL0;
+		break;
 	case SKL_DPLL1:
 		id = DPLL_ID_SKL_DPLL1;
 		break;