drm/amd/display: Fix reset sequence with driver direct DMCUB fw load

[Why]
DMCUB encounters a page fault/double exception with driver direct load
because DMCUB is not held in soft reset after releasing secure reset.

The clean shutdown sequence via GPINT is also not executed in this
sequence which leaves hardware behavior in an indeterminate state.

[How]
Move reset earlier in the sequence.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Anson Jacob <anson.jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>