drm/i915: placeholder getparam

There are internal patches for a feature which require a parameter to
query whether support exists . These patches cannot be made external
yet. In order to keep existing tests and userspace happy and free from
conflicts, reserve a number for it.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

include/drm/i915_drm.h

@@ -313,6 +313,7 @@ typedef struct drm_i915_irq_wait {
 #define I915_PARAM_HAS_WAIT_TIMEOUT	 19
 #define I915_PARAM_HAS_SEMAPHORES	 20
 #define I915_PARAM_HAS_PRIME_VMAP_FLUSH	 21
+#define I915_PARAM_RSVD_FOR_FUTURE_USE	 22
 
 typedef struct drm_i915_getparam {
 	int param;