drm/amd/display: move vmid determination logic out of dc

Currently vmid is decided internally inside dc. This makes it
difficult to use vmid use with external components.

This change moves vmid logic outside dc and allowing vmid to be
passed in as a parameter to DC.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>