drm/i915: Drop I915_ prefix from HAS_FBC

My OCD just couldn't let this slide. Spotted while reviewing Ville's
patch to only flip planes when we have FBC.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 88901e5..cf7922b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1844,7 +1844,7 @@
 
 #define HAS_FW_BLC(dev) (INTEL_INFO(dev)->gen > 2)
 #define HAS_PIPE_CXSR(dev) (INTEL_INFO(dev)->has_pipe_cxsr)
-#define I915_HAS_FBC(dev) (INTEL_INFO(dev)->has_fbc)
+#define HAS_FBC(dev) (INTEL_INFO(dev)->has_fbc)
 
 #define HAS_IPS(dev)		(IS_ULT(dev) || IS_BROADWELL(dev))