MIPS: BCM47xx: Update defconfig

Update Broadcom BCM47xx defconfig with:

- tiny RCU
- BCM47xx watchdog driver
- b43/b43legacy wireless as modules
- SSB Gigabit Ethernet driver
- disabled IRDA

6igned-off-by: Florian Fainelli <florian@openwrt.org>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1167/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>