Port Paulus's ppc64 fix to sh:

  When the generic IRQ stuff went in, it seems that HARDIRQ_BITS got bumped
  from 9 (for ppc64) up to 12.  Consequently, the PREEMPT_ACTIVE bit is now
  within HARDIRQ_MASK, and I get in_interrupt() falsely returning true when
  PREEMPT_ACTIVE is set, and thus a BUG_ON tripping in arch/ppc64/mm/tlb.c.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>