reset: hisilicon: Change to syscon register access

There are two reset controllers in hi6220 SoC:
The peripheral reset controller bits are part of sysctrl registers.
The media reset controller bits are part of mediactrl registers.

So change register access to syscon way.
And rename current reset controller to peripheral one.

Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
Signed-off-by: Xia Qing <saberlily.xia@hisilicon.com>
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>