EDAC/mce_amd: Always load on SMCA systems

MCA error decoding on SMCA systems is not dependent on family. Return
success early if the system supports the SMCA feature.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200110015651.14887-3-Yazen.Ghannam@amd.com