drm/i915: Move SKL IPC WA to HAS_IPC()

SKL has IPC but it should not be set according to the WA, so lets
just mark as it don't have it to simply the code and avoid
unnecessary MMIO writes at every call to intel_enable_ipc().

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180918204714.27306-4-jose.souza@intel.com

drivers/gpu/drm/i915/i915_pci.c

@@ -472,6 +472,8 @@ static const struct intel_device_info intel_cherryview_info = {
 
 #define SKL_PLATFORM \
 	GEN9_FEATURES, \
+	/* Display WA #0477 WaDisableIPC: skl */ \
+	.has_ipc = 0, \
 	PLATFORM(INTEL_SKYLAKE)
 
 static const struct intel_device_info intel_skylake_gt1_info = {

drivers/gpu/drm/i915/intel_pm.c

@@ -6120,10 +6120,6 @@ void intel_enable_ipc(struct drm_i915_private *dev_priv)
 	if (!HAS_IPC(dev_priv))
 		return;
 
-	/* Display WA #0477 WaDisableIPC: skl */
-	if (IS_SKYLAKE(dev_priv))
-		dev_priv->ipc_enabled = false;
-
 	/* Display WA #1141: SKL:all KBL:all CFL */
 	if ((IS_KABYLAKE(dev_priv) || IS_COFFEELAKE(dev_priv)) &&
 	    !dev_priv->dram_info.symmetric_memory)