x86: unify restore_fpu_checking

Impact: cleanup

On x86_32, separate f*rstor to an inline function which makes
restore_fpu_checking the same on both platforms -> move it
outside the ifdefs.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
LKML-Reference: <1239190320-23952-2-git-send-email-jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>