x86-32, smap: Add STAC/CLAC instructions to 32-bit kernel entry

The changes to entry_32.S got missed in checkin:

63bcff2a

 x86, smap: Add STAC and CLAC instructions to control user space access

The resulting kernel was largely functional but SMAP protection could
have been bypassed.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com