This patch add cose related to regulator. To control powre consumeption
have registered the voltage consumer of WM8994 to the regulator framework.

Additionally, I explain the constraints of the regulator of WM8994 codec.
All these consumer supply of WM8994 codec connected the regulator(VCC_1.8V)
on a circuit diagram. "VCC_1.8V" regulator is always enabled, because it is
used to many devices on Goni/Aquila board. This is required especially
when there are many devices physically attached to "VCC_1.8V" and some of
they did not "register" as consumers to "VCC_1.8V". "VCC_1.8V" might be
turned off by those who are registered while "unregistered" are still active
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>