Revert "ARM: dts: msm: keep refgen regulator always-on for SDM845 v2"

This reverts commit d388dd8c ("ARM: dts: msm: keep refgen
regulator always-on for SDM845 v2").

Now that display and camera devices are consumers of the refgen
regulator, remove the regulator-always-on flag.  This ensures that
power can be saved by disabling the refgen regulator when neither
consumer needs it to be enabled.

Change-Id: I0133be9f24647d7fc6542a9c3458d4bb2b8add05
Signed-off-by: David Collins <collinsd@codeaurora.org>