drm/amd/pm: expose the firmware_capability from firmware_info table

That will help to determine whether 2ND_USB20_PORT workaround is
needed for Sienna Cichlid.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>