kernel: b53: add support for GPIO reset

This is needed for some switches used on bcm47xx SoCs like the one on the Asus RT-N66U.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>


git-svn-id: svn://svn.openwrt.org/openwrt@37645 3c298f89-4303-0410-b956-a3cf2f4a3e73