x86, microcode, amd: Allow multiple families' bin files appended together

Add support for parsing through multiple families' microcode patch
container binary files appended together when early loading. This is
already supported on Intel.

Reported-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Link: http://lkml.kernel.org/r/1370463236-2115-3-git-send-email-jacob.shin@amd.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>