drm/omap: omap_irq: Fix a couple of doc-rot issues

The API has been updated, but the header was not.

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/omapdrm/omap_irq.c:115: warning: Function parameter or member 'crtc' not described in 'omap_irq_enable_vblank'
 drivers/gpu/drm/omapdrm/omap_irq.c:115: warning: Excess function parameter 'dev' description in 'omap_irq_enable_vblank'
 drivers/gpu/drm/omapdrm/omap_irq.c:115: warning: Excess function parameter 'pipe' description in 'omap_irq_enable_vblank'
 drivers/gpu/drm/omapdrm/omap_irq.c:142: warning: Function parameter or member 'crtc' not described in 'omap_irq_disable_vblank'
 drivers/gpu/drm/omapdrm/omap_irq.c:142: warning: Excess function parameter 'dev' description in 'omap_irq_disable_vblank'
 drivers/gpu/drm/omapdrm/omap_irq.c:142: warning: Excess function parameter 'pipe' description in 'omap_irq_disable_vblank'

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Rob Clark <rob.clark@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105144517.1826692-5-lee.jones@linaro.org

drivers/gpu/drm/omapdrm/omap_irq.c

@@ -100,8 +100,7 @@ int omap_irq_enable_framedone(struct drm_crtc *crtc, bool enable)
 
 /**
  * enable_vblank - enable vblank interrupt events
- * @dev: DRM device
- * @pipe: which irq to enable
+ * @crtc: DRM CRTC
  *
  * Enable vblank interrupts for @crtc.  If the device doesn't have
  * a hardware vblank counter, this routine should be a no-op, since
@@ -131,8 +130,7 @@ int omap_irq_enable_vblank(struct drm_crtc *crtc)
 
 /**
  * disable_vblank - disable vblank interrupt events
- * @dev: DRM device
- * @pipe: which irq to enable
+ * @crtc: DRM CRTC
  *
  * Disable vblank interrupts for @crtc.  If the device doesn't have
  * a hardware vblank counter, this routine should be a no-op, since