drm/amd/display: Correct the plane enumeration order (v2)

The order of planes is given by the order they are enumerated
by kms.
Planes with a higher ID appears above planes with a lower ID.

Currently the planes are enumerated in the wrong order,
putting the nv12 only plane after the two RGBA planes.

This patch corrects the plane enumeration order such that all
the overlay planes are initialized first then the primary planes.

Due to this change in order the dc_add_plane_to_context() shall
receive the planes in reverse order hence this patch reverses
the parsing of planes in DM side itself.

v2: drop local reverse macro for upstream

Signed-off-by: Shirish S <shirish.s@amd.com>
Signed-off-by: Pratik Vishwakarma <Pratik.Vishwakarma@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>