arm/dt: 8226: Device tree nodes for gdsc

Add devices for gdsc regulators present on 8226. Disable all gdscs
by default, and only enable gdscs which are present on a per device
basis.

Change-Id: I0fbf1a76320d13b51385b6db2853fed1863ed00f
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>