MIPS: ralink: Add support for reset-controller API

Add a helper for reseting different devices on the SoC.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5804/
Patchwork: https://patchwork.linux-mips.org/patch/5797/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>