Make it global so we can convert specific mca address.

v2: rename query_error_address_per_channel to
convert_ras_error_address
Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>