MIPS: ath79: Add AR933X specific glue for ath79_device_reset_{set,clear}

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Kathy Giori <kgiori@qca.qualcomm.com>
Cc: "Luis R.  Rodriguez" <rodrigue@qca.qualcomm.com>
Patchwork: https://patchwork.linux-mips.org/patch/2523/


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