Add qpnp-flash-v2 driver for kona.
This is taken as a snapshot from msm-5.4 kernel
'commit 40ccd6775f80 ("qpnp-flash-v2: Add
support for qpnp-flash-v2 driver")'.
Also, replace the iio_channel_get with devm_iio_channel_get.
Change-Id: I90bfda0ace7b86deb96efac169978c6fb7f8fa23
Signed-off-by: Zihang Hu <quic_zihahu@quicinc.com>