x86/microcode: Ensure that module is only loaded on supported Intel CPUs

Exit early when there's no support for a particular CPU family.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: tigran@aivazian.fsnet.co.uk
Cc: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/4F8BDB58.6070007@linux.vnet.ibm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>