ralink: add dwc2 reset patch

this allows people building custom images to use dwc2 instead of dwc_otg

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@42801 3c298f89-4303-0410-b956-a3cf2f4a3e73