drm/i915/bxt: Update revision id for BXT C0

Cc: Nick Hoath <nicholas.hoath@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2507,7 +2507,7 @@ struct drm_i915_cmd_table {
 
 #define BXT_REVID_A0		(0x0)
 #define BXT_REVID_B0		(0x3)
-#define BXT_REVID_C0		(0x6)
+#define BXT_REVID_C0		(0x9)
 
 /*
  * The genX designation typically refers to the render engine, so render