Update the serial_txx9 driver.

 * More strict check in verify_port.  Cleanup.
 * Do not insert a char caused previous overrun.
 * Fix some spin_locks.
 * Do not call uart_add_one_port for absent ports.

Also, this patch removes a BROKEN tag from Kconfig.  This driver has been
marked as BROKEN by removal of uart_register_port, but it has been solved
already on Sep 2005.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>