power: qpnp-fg-gen4: Add snapshot of driver and its dependencies

Add snapshot of the qpnp-fg-gen4 driver as of msm-4.14
'commit 7e16ff6cdde5 ("defconfig: qcs405: enable WLAN configs
for 32-bit QCS405")'.

This driver adds support for the GEN4 Fuel Gauge (FG) peripheral that is
present on PM8150B and similar chips. The FG measures and provides
various battery parameters like Voltage, Current, State of Charge,
Temperature to the clients upon request.

Changed use of cancel_work() to cancel_work_sync() as the former has
been made obsolete.

Change-Id: I60c7476e95e660507447e9a256bf3fcde6bb335c
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>