Use drm_crtc_mask() where appropriate.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/1610335818-32895-1-git-send-email-tiantao6@hisilicon.com