drm: mali-dp: Check more use cases in the plane's ->atomic_check()

Mali DP's plane ->atomic_check() only checks for the new state submitting
frame buffers with supported pixel formats and if there is enough
rotation memory for rotated planes. Add a call to
drm_plane_helper_check_state() to add additional checks for plane
state validity and clipping issues.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>