drm/amd/pm: Use metric table for pcie speed/width

drm/amd/pm: Use metric table for pcie speed/width

Report pcie link speed/width using metric table in case
of one vf & if pmfw support is available, else report directly from
registers in case of pf. Skip reporting it for other cases.

v2: Skip multi-vf check(Lijo)

Signed-off-by: Asad Kamal <asad.kamal@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>