nvmem: sunxi: Move the SID driver to the nvmem framework

Now that we have the nvmem framework, we can consolidate the common
driver code. Move the driver to the framework, and hopefully, it will
fix the sysfs file creation race.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
[srinivas.kandagatla: Moved to regmap based EEPROM framework]
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>