ARM: dts: msm: Modify LDO12A "init-voltage" to 1.8V for lagoon

As LDO12A is PON regulator, setting the "init-voltage" less than
the default voltage leads to momentary voltage dip on the LDO12A
output. To avoid this behaviour, set the "init-voltage" to a
default recommended value of 1.8V.

Change-Id: I47b735615af1182463001bae59a78be24734bc0f