drm/atomic: use drm_crtc_vblank_waitqueue()

drm/atomic: use drm_crtc_vblank_waitqueue()

We have drm_crtc_vblank_waitqueue() to get the wait_queue_head_t pointer
for a vblank. Use it instead of poking at dev->vblank[] directly.

Due to the macro maze of wait_event_timeout() that uses the address-of
operator on the argument, we have to pass it in with the indirection
operator.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/1097348197acea9110da8baebbbc189890d01660.1762513240.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>