EDAC/amd64: Drop some family checks for newer systems

In general, "pvt->umc != NULL" is used to check if the system is Family
17h+. However, there are a few places that are using direct family
checks.

Replace the remaining family checks with a check for "pvt->umc != NULL".

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200110015651.14887-6-Yazen.Ghannam@amd.com