drm: fix documentation for drm_crtc_set_mode()

commit 4c9287c6 upstream.

x and y parameters are offsets, not width/height
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/drm_crtc_helper.c

@@ -321,8 +321,8 @@ drm_crtc_prepare_encoders(struct drm_device *dev)
  * drm_crtc_set_mode - set a mode
  * @crtc: CRTC to program
  * @mode: mode to use
- * @x: width of mode
- * @y: height of mode
+ * @x: horizontal offset into the surface
+ * @y: vertical offset into the surface
  *
  * LOCKING:
  * Caller must hold mode config lock.