hwmon: qpnp-adc-common: Reduce kernel error prints

Update the revid check to use pr_debug instead of
pr_err to reduce potential errors to get printed.
This is an optional property as far is IADC is concerned
to apply temperature compensation for the supported chips.

Change-Id: I77036fb9f0eb640e43216762461ba036b2aa0caf
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>