drm/amd/display: Ensure that DMCUB fw in use is loaded by DC and not VBIOS

[Why?]
On wake from S3/S4, driver checks if DMUB is initialized. On S4 VBIOS loads
DMUB, and driver does not reload as it appears to be initialized already.

[How?]
Add a check for the DAL_FW bit to ensure that loaded FW is from driver and
not VBIOS.

Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>