drm: Fix warning with make xmldocs caused by drm_irq.c

This patch fix following warnings.

Warning(.//drivers/gpu/drm/drm_irq.c:1279): No description
found for parameter drm_crtc'
Warning(.//drivers/gpu/drm/drm_irq.c:1279): Excess function
parameter 'crtc' description in 'drm_crtc_vblank_reset'

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_irq.c

@@ -1267,7 +1267,7 @@ EXPORT_SYMBOL(drm_crtc_vblank_off);
 
 /**
  * drm_crtc_vblank_reset - reset vblank state to off on a CRTC
- * @crtc: CRTC in question
+ * @drm_crtc: CRTC in question
  *
  * Drivers can use this function to reset the vblank state to off at load time.
  * Drivers should use this together with the drm_crtc_vblank_off() and