MAINTAINERS: ARM: SiRF: use regex patterns to involve all SiRF drivers

instead of listing drivers one by one, use regex patterns to involve all
SiRF drivers directly.
this also adds sirf UART and watchdog drivers automatically from:
drivers/tty/serial/sirfsoc_uart.*
drivers/watchdog/sirfsoc_wdt.c

Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Olof Johansson <olof@lixom.net>