reset: sunxi: use reset-simple driver

Use the newly created copies in the reset-simple driver to replace the
sunxi platform driver code and reset operations. The separate sunxi
driver still remains to register the early reset controllers, but it
reuses the reset operations in reset-simple.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Alexandru Gagniuc <alex.g@adaptrum.com>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>