drm/i915/plane: drop atomic from intel_atomic_plane_check_clipping()

Align with intel_plane_check_src_coordinates(). The "atomic" is
superfluous.

Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://lore.kernel.org/r/0bebd67e583b6ca56f788bd795ffe77db342e809.1750147992.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>