drm/i915: Get correct display clock on 945gm

This is according to Mobile Intel® 945 Express Chipset
Family datasheet.

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Link: http://patchwork.freedesktop.org/patch/msgid/20170131235026.26003-1-arthur@aheymans.xyz
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a9538ae..4b5761d 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -119,7 +119,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define GCFGC	0xf0 /* 915+ only */
 #define   GC_LOW_FREQUENCY_ENABLE	(1 << 7)
 #define   GC_DISPLAY_CLOCK_190_200_MHZ	(0 << 4)
-#define   GC_DISPLAY_CLOCK_333_MHZ	(4 << 4)
+#define   GC_DISPLAY_CLOCK_333_320_MHZ	(4 << 4)
 #define   GC_DISPLAY_CLOCK_267_MHZ_PNV	(0 << 4)
 #define   GC_DISPLAY_CLOCK_333_MHZ_PNV	(1 << 4)
 #define   GC_DISPLAY_CLOCK_444_MHZ_PNV	(2 << 4)