da9052-battery: Avoid out-of-range array access

Avoid accessing vc_tbl_ref[3], which is one past the end of that array, in
da9052_determine_vc_tbl_index(), by adjusting the loop bound.

(Hint: there is 'i + 1' inside the loop.)

Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>