[Why]
Store these in advance so we can reuse them later in commit_tail without
having to reserve the fbo again.

These will also be used for checking for tiling changes when deciding
to reset the plane or not.

[How]
This change should mostly be a refactor. Only commit check is affected
for now and I'll drop the get_fb_info calls in prepare_planes and
commit_tail after.

This runs a prepass loop once we think that all planes have been added
to the context and replaces the get_fb_info calls with accessing the
dm_plane_state instead.
Signed-off-by: NNicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>