x86, AMD: Convert to the new bit access MSR accessors

... and save us a bunch of code.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1394384725-10796-3-git-send-email-bp@alien8.de


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