regulator: ab8500: Separate regulator and MFD platform data

The ab8500 MFD should not have knowledge about regulator-
specific platform data like number of regulators and
regulator registers. As the regulator platform data is
about to grow with external regulators, this information
is moved to a new structure provided by the regulator
driver.

Signed-off-by: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Yvan FILLION <yvan.fillion@stericsson.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>