drm/amd/display: Do DMCUB hw_init before DC

[Why]
For DMCUB enabled hardware DC has a dependency on DMCUB already being
running.

Command table offloading will fail on first modeset if DMCUB isn't
initialized first.

[How]
Perform DMCUB hardware initialization before DC.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>