arm/dt: Add regulator properties to DSI device

DSI controller and the DSI PLL are powered by
these regulators. Fix the memory map region
to include only DSI-0 controller related registers.

Change-Id: I92c387b1d639ec1c50a5ee5406b702f4325774f6
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>