m68knommu: avoid unneccessary use of xchg() in set_mb()

Avoid unneccessary use of xchg() in set_mb().

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed