[PATCH] optimise 64bit unaligned access on 32bit kernel

I've rewriten Atushi's fix for the 64-bit put_unaligned on 32-bit systems
bug to generate more efficient code.

This case has buzilla URL http://bugzilla.kernel.org/show_bug.cgi?id=5138

.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>