[PATCH] serial: update NEC VR4100 series serial support

- Changed the return value of unknown type to NULL.

- Deleted the NULL check of dev_id in siu_interrupt().

- Deleted the NULL check of port->membase in siu_shutdown().

- Added the NULL check of port->membase to siu_startup().

- Removed early_uart_ops. Now using vr41xx_siu standerd one.

- Changed KSEG1ADDR() in siu_console_setup() to ioremap().

- When uart_add_one_port() failed, changed to set NULL to port->dev.

Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.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>