drm/i915: add GETPARAM request for page flipping

Add a GETPARAM request for checking if page flipping is supported.
Useful for the 2D driver to enable the flipping path.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index c900499..1b4f3a5 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -271,6 +271,7 @@
 #define I915_PARAM_HAS_GEM               5
 #define I915_PARAM_NUM_FENCES_AVAIL      6
 #define I915_PARAM_HAS_OVERLAY           7
+#define I915_PARAM_HAS_PAGEFLIPPING	 8
 
 typedef struct drm_i915_getparam {
 	int param;