regulator: Add Anatop regulator driver

Anatop is an integrated regulator inside i.MX6 SoC.
There are 3 digital regulators which controls PU, CORE (ARM), and SOC.
And 3 analog regulators which controls 1P1, 2P5, 3P0 (USB).
This patch adds the Anatop regulator driver.

Signed-off-by: Nancy Chen <Nancy.Chen@freescale.com>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>