hwmon: qpnp-adc-tm: Add version check for VADC_TM channel

vph_pwr channel should be supported for VADC_TM for pm8950 2.0.
Add version check to detect the PMIC used and support channel
accordingly.

Change-Id: I1e0a0a269e9e0f164150766a5dabaf51791b21cc
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>