x86/microcode/AMD: Convert early parser to the new verification routines

Now that they have the required functionality, use them to verify the
equivalence table and each patch, thus making parse_container() more
readable.

Originally-by: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: x86@kernel.org
Link: https://lkml.kernel.org/r/20181107170218.7596-12-bp@alien8.de