drm/amdgpu: Add support for CPERs on virtualization

Add support for CPERs on VFs.

VFs do not receive PMFW messages directly; as such, they need to
query them from the host. To avoid hitting host event guard,
CPER queries need to be rate limited. CPER queries share the same
RAS telemetry buffer as error count query, so a mutex protecting
the shared buffer was added as well.

For readability, the amdgpu_detect_virtualization was refactored
into multiple individual functions.

Signed-off-by: Tony Yi <Tony.Yi@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>