drm/amd/display: Fix mismatched unlock for DMUB HW lock in HWSS fast path

drm/amd/display: Fix mismatched unlock for DMUB HW lock in HWSS fast path

[Why]
The evaluation for whether we need to use the DMUB HW lock isn't the
same as whether we need to unlock which results in a hang when the
fast path is used for ASIC without FAMS support.

[How]
Store a flag that indicates whether we should use the lock and use
that same flag to specify whether unlocking is needed.

Reviewed-by: Swapnil Patel <swapnil.patel@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>