[PATCH] ppc32: remove cli()/sti() in arch/ppc/4xx_io/serial_sicc.c

Replace save_flags()/restore_flags() with
spin_lock_irqsave()/spin_unlock_irqrestore() and document reasons for using
spinlocks.
Signed-off-by: James Nelson <james4765@gmail.com>
Signed-off-by: Tom Rini <trini@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>