drm/omap: add sanity plane state check

Call drm_atomic_helper_check_plane_state() from the plane
atomic_check() callback in order to add plane state sanity
checking.

It will permit filtering out totally bad scaling factors, even
if the real check are done later in the atomic commit.

Calling drm_atomic_helper_check_plane_state() also sets
plane_state->visible which will be useful when dynamically
assigning hw overlays to planes.

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211117141928.771082-2-narmstrong@baylibre.com