ARM: dts: msm: add PMi8994 PON as a secondary PON device

As per the recommendation from the hardware team, during system reset,
secondary PMIC's PON should be configured in the same way as that of
the primary PMIC PM8994. Hence add the PON device for PMi8994 and
configure it as a secondary PON device.

CRs-Fixed: 768664
Change-Id: I39feedccd003fcc784518c8362c62246b1090c72
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>