power: qpnp-bms: clean up vbatt functions

Currently the BMS has multiple functions for reading VBAT_SNS from
VADC. There is no reason for this. Change them all to use only one
function and delete the rest.

Change-Id: I5438907537b86a296d8564a491a98f50ba937b90
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>
1 file changed