drm/amd/display: add gpio lock/unlock

[Why]
When querying HPD via GPIO flow,
it will create a new gpio object then free in the end of query.
There is a irql issue for HPD querying at ISR level.

[How]
Therefore, creating the HPD gpio object in dc_link and set it as unlcok in default.
1. reducing unnecessary malloc/free when HPD querying.
2. reducing init GPIO flow.
3. add lock/unlock to prevent multi gpio service running.

Signed-off-by: Chiawen Huang <chiawen.huang@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>