regmap: Separate regmap dev initialization

Create special function regmap_attach_dev
which can be called separately out of regmap_init.

Signed-off-by: Michal Simek <michal.simek@xilinx.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