drm/i915: Clean up SKL_BOTTOM_COLOR defines

Use REG_BIT() for SKL_BOTTOM_COLOR.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211112193813.8224-4-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -5341,8 +5341,8 @@ enum {
 
 /* Skylake+ pipe bottom (background) color */
 #define _SKL_BOTTOM_COLOR_A		0x70034
-#define   SKL_BOTTOM_COLOR_GAMMA_ENABLE	(1 << 31)
-#define   SKL_BOTTOM_COLOR_CSC_ENABLE	(1 << 30)
+#define   SKL_BOTTOM_COLOR_GAMMA_ENABLE		REG_BIT(31)
+#define   SKL_BOTTOM_COLOR_CSC_ENABLE		REG_BIT(30)
 #define SKL_BOTTOM_COLOR(pipe)		_MMIO_PIPE2(pipe, _SKL_BOTTOM_COLOR_A)
 
 #define _ICL_PIPE_A_STATUS			0x70058