power: ab8500_fg: Fix build warning

Fix

drivers/power/ab8500_fg.c: In function 'ab8500_fg_probe':
drivers/power/ab8500_fg.c:2989:27:
		warning: 'i' may be used uninitialized in this function
drivers/power/ab8500_fg.c:2972:15: note: 'i' was declared here

which actually points to a real bug.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>