MIPS: AR7: Update defconfig

Update Texas Instruments AR7 defconfig with:

- tiny RCU
- LEDs GPIO
- disable SSB
- enable zboot support
- enable GPIO sysfs support
Signed-off-by: Florian Fainelli <florian@openwrt.org>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1165/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>