arm/dt: msmcopper: Mark several PM8841 and PM8941 regulators as always-on

The following regulators must be enabled at all times in order
for the Copper system to operate:
PM8841: S1 and S2
PM8941: S1, S3, and L1

Configure these regulators in msmcopper-regulator.dtsi so that
they are always on.

Additionally set PM8841 S5 to be always on so that it cannot be
disabled before the necessary software is in place to handle it.

Change-Id: Ifb67463cba72bda0055282782966a0b272357870
Signed-off-by: David Collins <collinsd@codeaurora.org>