drm/i915/psr: New power domain for AUX IO.

PSR on CNL requires AUX IO wells to be kept on and the existing AUX domain
for AUX-A enables DC_OFF well too. This is not required, so add a new
AUX_IO_A domain for AUX-A to allow DC states to remain enabled. Other AUX
channels re-use the existing AUX domains.

v4: Reword comment (Rodrigo and Ville)
    Rename _get and _put functions to include aux_io substring(Rodrigo)
    Remove unnecessary diff that got included.
v3: Extract aux domain selection into a function (Ville)
v2: Add AUX IO domain only for AUX-A
    Rebased on top of Ville's AUX series.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Suggested-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180223221520.18464-1-dhinakaran.pandiyan@intel.com
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index b7924fe..53ea564 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -130,6 +130,8 @@ intel_display_power_domain_str(enum intel_display_power_domain domain)
 		return "AUX_D";
 	case POWER_DOMAIN_AUX_F:
 		return "AUX_F";
+	case POWER_DOMAIN_AUX_IO_A:
+		return "AUX_IO_A";
 	case POWER_DOMAIN_GMBUS:
 		return "GMBUS";
 	case POWER_DOMAIN_INIT:
@@ -1853,6 +1855,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	BIT_ULL(POWER_DOMAIN_INIT))
 #define CNL_DISPLAY_AUX_A_POWER_DOMAINS (		\
 	BIT_ULL(POWER_DOMAIN_AUX_A) |			\
+	BIT_ULL(POWER_DOMAIN_AUX_IO_A) |		\
 	BIT_ULL(POWER_DOMAIN_INIT))
 #define CNL_DISPLAY_AUX_B_POWER_DOMAINS (		\
 	BIT_ULL(POWER_DOMAIN_AUX_B) |			\