power: qpnp-charger: remove revision check for temperature reads

The revision register is not sufficient enough to distinguish
whether the ADC is available or not.

Fix this by removing this check to allow the ADC driver to
handle whether the temperature reading is available or not.

CRs-Fixed: 500673
Change-Id: I4ec2fbfb3ef5f70e8461ae4467492157f319540e
Signed-off-by: David Keitel <dkeitel@codeaurora.org>