x86, microcode: Straighten out Kconfig text

Update and clarify Kconfig help text along with menu names.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1344361461-10076-6-git-send-email-bp@amd64.org


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