hwmon: qpnp-adc: Fix incorrect 625mV channel read

Incorrect 625mV channel reads results into sudden
BMS SOC jumps and device shutdown.

Fix the problem by resetting the status variable
on each ADC channel read.

Change-Id: I12afcb32cb684c830ed14a444a1aec49aa18f846
Signed-off-by: Dipen Parmar <dipenp@codeaurora.org>