drivers/serial/mrst_max3110.c needs linux/irq.h

sparc64 allmodconfig:

  drivers/serial/mrst_max3110.c: In function `serial_m3110_startup':
  drivers/serial/mrst_max3110.c:470: error: `IRQ_TYPE_EDGE_FALLING' undeclared (first use in this function)

Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>