drm/blend: Fix comment typ-o

Fix DRM_REFELCT_Y -> DRM_REFLECT_Y.
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170519205017.23307-1-robert.foss@collabora.com

drivers/gpu/drm/drm_blend.c

@@ -129,7 +129,7 @@
  * 	"rotate-270"
  * DRM_REFLECT_X:
  * 	"reflect-x"
- * DRM_REFELCT_Y:
+ * DRM_REFLECT_Y:
  * 	"reflect-y"
  *
  * Rotation is the specified amount in degrees in counter clockwise direction,