ARM: dts: enable ldo mode for apq8084, msm8974 and msm8974 pro

The LDO mode was disabled because the secondary GFMUX was not programmed
and putting the device in LDO mode switches the core to use the
secondary GFMUX.

The clock driver is updated to configure the secondary GFMUX, it is
now safe to use it.

Change-Id: I5e2ce896f33fdb79a277d5688c9e725ee6f62b97
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>