power: pm8921-bms: fix division error

Arithmetic conversion rules states that a signed operand is converted
to unsigned if the other operand is unsigned.

The voltage across vsense is a signed int and it can be negative.
Dividing it by the battery sense resistor, an unsigned int,  was
resulting in a very large positive number instead of a negative number.

Fix it by casting the battery sense resistor to signed so that a
a signed division is performed.

Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
diff --git a/drivers/power/pm8921-bms.c b/drivers/power/pm8921-bms.c
index 7c73c23..3a34a6a 100644
--- a/drivers/power/pm8921-bms.c
+++ b/drivers/power/pm8921-bms.c
@@ -872,7 +872,8 @@
 
 	read_vsense_avg(the_chip, result);
 	pr_debug("vsense=%d\n", *result);
-	*result = *result / the_chip->r_sense;
+	/* cast for signed division */
+	*result = *result / (int)the_chip->r_sense;
 	return 0;
 }
 EXPORT_SYMBOL(pm8921_bms_get_battery_current);