watchdog: mtk_wdt: mt2712: Add reset controller

Add reset controller for 2712.
Besides watchdog, MTK toprgu module alsa provide sub-system (eg, audio,
camera, codec and connectivity) software reset functionality.

Signed-off-by: yong.liang <yong.liang@mediatek.com>
Signed-off-by: Jiaxin Yu <jiaxin.yu@mediatek.com>
Reviewed-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20200115085828.27791-5-yong.liang@mediatek.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>