nvmem: sunxi_sid: Dynamically allocate nvmem_config structure

The sunxi_sid driver currently uses a statically allocated nvmem_config
structure that is updated at probe time. This is sub-optimal as it
limits the driver to one instance, and also takes up space even if the
device is not present.

Modify the driver to allocate the nvmem_config structure at probe time,
plugging in the desired parameters along the way.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>