drm/amd/display: Add ODM check during pipe split/merge validation

[why]
When querying DML for a vlevel after pipes have been split or merged the
ODM policy would revert to a default policy, which could cause the query
to use the incorrect ODM status. In this case ODM 2to1 was validated,
but the last DML query would assume no ODM and return the incorrect
vlevel.

[how]
Added ODM check to apply the correct ODM policy before querying DML.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Relja Vojvodic <relja.vojvodic@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>