Update the serial_txx9 driver.

 * Configurable manumum port number. (SERIAL_TXX9_NR_UARTS)
 * Remove some code which is unneeded if CONFIG_PM=n.
 * Use PCI_DEVICE() for pci device id table and make it const.
 * Do not include <asm/irq.h>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>