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

In the Linux kernel, the following vulnerability has been resolved:

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.