rebase tx49 serial fixes

This is a rebase to 2.6.16.1 of the 2.6.16-rc1-mm5 patch serial-serial_txx9-driver-update.patch.

http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.16-rc1/2.6.16-rc1-mm5/broken-out/serial-serial_txx9-driver-update.patch

From: Atsushi Nemoto <[email protected]>

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.

Index: linux-2.6.16.1/drivers/serial/Kconfig
===================================================================
@@ -859,7 +859,7 @@
 
 config SERIAL_TXX9
 	bool "TMPTX39XX/49XX SIO support"
-	depends HAS_TXX9_SERIAL && BROKEN
+	depends HAS_TXX9_SERIAL
 	select SERIAL_CORE
 	default y