ARM: S5PV210: Add voltage consumer of WM8994 to the regulator framework

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>