drm/omap: Switch omapdrm over to drm_mode_create_rotation_property()

Use the new drm_mode_create_rotation_property() in omapdrm.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Sagar Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>