drm/i915: create VLV_DSIPLAY_BASE #define

Will be used more in the next patch.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -1031,7 +1031,7 @@ static bool IS_DISPLAYREG(u32 reg)
 	 * This should make it easier to transition modules over to the
 	 * new register block scheme, since we can do it incrementally.
 	 */
-	if (reg >= 0x180000)
+	if (reg >= VLV_DISPLAY_BASE)
 		return false;
 
 	if (reg >= RENDER_RING_BASE &&

drivers/gpu/drm/i915/i915_reg.h

@@ -529,6 +529,8 @@
 #define   GFX_PSMI_GRANULARITY		(1<<10)
 #define   GFX_PPGTT_ENABLE		(1<<9)
 
+#define VLV_DISPLAY_BASE 0x180000
+
 #define SCPD0		0x0209c /* 915+ only */
 #define IER		0x020a0
 #define IIR		0x020a4