Using .format_write means, we have a custom function to write to the
chip, but not to read back. Also, mark registers as "not precious" and
"not volatile" which is implicit because we cannot read them. Make those
functions use 'regmap_readable' to reuse the checks done there.
Signed-off-by: NWolfram Sang <w.sang@pengutronix.de>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>