drm: annotate drm_core_check_feature() dev arg. as const

This static inline function doesn't modify any state.

Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: NEmil Velikov <emil.velikov@collabora.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114085408.15933-1-emil.l.velikov@gmail.com

include/drm/drm_drv.h

@@ -666,7 +666,7 @@ static inline bool drm_dev_is_unplugged(struct drm_device *dev)
  *
  * Returns true if the @feature is supported, false otherwise.
  */
-static inline bool drm_core_check_feature(struct drm_device *dev, u32 feature)
+static inline bool drm_core_check_feature(const struct drm_device *dev, u32 feature)
 {
 	return dev->driver->driver_features & dev->driver_features & feature;
 }