drm/i915: Define skl+ palette anti-collision bit

I've been frobbing the palette anti-collision logic bit
while playing around with DSB. Not sure we'll have real
use for this but let's define the bit anyways so I don't
have to carry it around locally.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221123152638.20622-4-ville.syrjala@linux.intel.comReviewed-by: Uma Shankar <uma.shankar@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -5310,6 +5310,7 @@
 #define GAMMA_MODE(pipe) _MMIO_PIPE(pipe, _GAMMA_MODE_A, _GAMMA_MODE_B)
 #define  PRE_CSC_GAMMA_ENABLE			REG_BIT(31) /* icl+ */
 #define  POST_CSC_GAMMA_ENABLE			REG_BIT(30) /* icl+ */
+#define  PALETTE_ANTICOL_DISABLE		REG_BIT(15) /* skl+ */
 #define  GAMMA_MODE_MODE_MASK			REG_GENMASK(1, 0)
 #define  GAMMA_MODE_MODE_8BIT			REG_FIELD_PREP(GAMMA_MODE_MODE_MASK, 0)
 #define  GAMMA_MODE_MODE_10BIT			REG_FIELD_PREP(GAMMA_MODE_MODE_MASK, 1)