gpu: drm: Fix warning caused by a parameter description in drm_crtc.c

This patch fix following error while "make xmldocs"

Warning(.//drivers/gpu/drm/drm_crtc.c:778): Excess function parameter
 'mode' description in 'drm_connector_get_cmdline_mode'
Signed-off-by: NMasanari Iida <standby24x7@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -766,7 +766,6 @@ static void drm_mode_remove(struct drm_connector *connector,
 /**
  * drm_connector_get_cmdline_mode - reads the user's cmdline mode
  * @connector: connector to quwery
- * @mode: returned mode
  *
  * The kernel supports per-connector configration of its consoles through
  * use of the video= parameter. This function parses that option and