regmap: Mark reg_defaults in regmap_multi_reg_write as const

There should be no need for the writes supplied to this function to be
edited by it so mark them as const.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --cc drivers/base/regmap/regmap.c
Simple merge

diff --cc include/linux/regmap.h
Simple merge