power: qpnp-smbcharger: fix bug in find_closest_in_array

This method uses a variable to track the current closest value's
index. The implementation was checking the distance between the
value and this index instead of the value at that index. Fix
this bug.

CRs-Fixed: 923805
Change-Id: Iac3cc125c4c5fabbe027ec38890d5c47e199187e
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>