drivers: qpnp-qg: Add snapshot of the QPNP QG driver

Snapshot of the QG driver from 4.9 kernel.
'commit cc0c4237e25d ("ARM: dts: msm: update SMB1355
device node inclusion policy")'.

Fix compilation issues for ADC calls, moving them to
IIO framework.

Change-Id: I63c3cd54f934d1042b2191bf60add07c3442a76f
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>