sgi-xp: nested calls to spin_lock_irqsave()

The code here has a nested spin_lock_irqsave().  It's not needed since
IRQs are already disabled and it causes a problem because it means that
IRQs won't be enabled again at the end.  The second call to
spin_lock_irqsave() will overwrite the value of irq_flags and we can't
restore the proper settings.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>