Provide drm_univeral_plane_alloc() to allocate and initialize a
plane. Code for non-atomic drivers uses this pattern. Convert them to
the new function. The modeset helpers contain a quirk for handling their
color formats differently. Set the flag outside plane allocation.

The new function is already deprecated to some extend. Drivers should
rather use drmm_univeral_plane_alloc() or drm_universal_plane_init().

v2:
	* kerneldoc fixes (Javier)
	* grammar fixes in commit message
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com> # nouveau
Link: https://patchwork.freedesktop.org/patch/msgid/20220909105947.6487-3-tzimmermann@suse.de