x86/microcode/AMD: Clean up per-family patch size checks

Starting with family 0x15, the patch size verification is not needed
anymore. Thus get rid of the need to update this checking function with
each new family.

Keep the check for older families.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Link: https://lkml.kernel.org/r/20181107170218.7596-5-bp@alien8.de