nvmem: sfp: Use regmap

nvmem: sfp: Use regmap

This converts the SFP driver to use regmap. This will allow easily
supporting devices with different endians. We disallow byte-level
access, as regmap_bulk_read doesn't support it (and it's unclear what
the correct result would be when we have an endianness difference).

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220429162701.2222-16-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>