EDAC/amd64: Remove scrub rate control for Family 17h and later

The scrub registers on AMD Family 17h and later may be inaccessible to
the OS. Furthermore, hardware designers recommend that the scrubbing
feature is managed by the firmware.

Remove support for the sdram_scrub_rate interface for AMD Family 17h
systems and later by not setting the scrub function pointers. The EDAC MC
core will then not expose the scrub files in sysfs.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230127170419.1824692-3-yazen.ghannam@amd.com