drm/i915/gen8: Add gen8_init_workarounds for common WA

WA in this function should be ordered based on register address.
The following order is suggested (Ville),

instpm
mi_mode
row chicken
half slice chicken
common slice chicken
hdc chicken
cache_mode_0
cache_mode_1
gt_mode

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -800,11 +800,22 @@ static int wa_add(struct drm_i915_private *dev_priv,
 
 #define WA_WRITE(addr, val) WA_REG(addr, 0xffffffff, val)
 
+static int gen8_init_workarounds(struct intel_engine_cs *ring)
+{
+
+	return 0;
+}
+
 static int bdw_init_workarounds(struct intel_engine_cs *ring)
 {
+	int ret;
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	ret = gen8_init_workarounds(ring);
+	if (ret)
+		return ret;
+
 	WA_SET_BIT_MASKED(INSTPM, INSTPM_FORCE_ORDERING);
 
 	/* WaDisableAsyncFlipPerfMode:bdw */
@@ -868,9 +879,14 @@ static int bdw_init_workarounds(struct intel_engine_cs *ring)
 
 static int chv_init_workarounds(struct intel_engine_cs *ring)
 {
+	int ret;
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	ret = gen8_init_workarounds(ring);
+	if (ret)
+		return ret;
+
 	WA_SET_BIT_MASKED(INSTPM, INSTPM_FORCE_ORDERING);
 
 	/* WaDisableAsyncFlipPerfMode:chv */