drm/i915: Silence sparse by using gfp_t

Sparse enforces that GFP flags are only manipulated inside gfp_t locals.

Fixes: 4d470f73 ("drm/i915: Avoid undefined behaviour of "u32 >> 32"")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170901145729.21363-1-chris@chris-wilson.co.ukReviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -290,7 +290,7 @@ static int eb_create(struct i915_execbuffer *eb)
 		 * direct lookup.
 		 */
 		do {
-			unsigned int flags;
+			gfp_t flags;
 
 			/* While we can still reduce the allocation size, don't
 			 * raise a warning and allow the allocation to fail.