ARM: dts: msm: Add LDO device configuration for MSM8994

The ldo device node contains the registers and the ldo retention value
that the registers need to be programmed to at coldboot to allow cpu
retention.

Change-Id: I57399e7ca17205f7c5a4acd1e0d05f8fe68b9b76
Signed-off-by: Karthik Parsha <kparsha@codeaurora.org>