ENGR00288351 sabresd_battery: fix usb charger detect when resume back on mx6sl

ENGR00288351 sabresd_battery: fix usb charger detect when resume back on mx6sl

Fix  below redundant log after first resume back on mx6slevk:
max8903-charger max8903.12: USB Charger Connected

It's caused by not add enough prepare for uok&dok which are connected, such as
i.MX6SL-EVK. In this case the board only support DC charger detect, so we
didn't need judge the uok pin for USB charger detect, although uok share with
dok pin.

Signed-off-by: Robin Gong <b38343@freescale.com>