mfd: rn5t618: Fix caching of battery related registers

Battery status changes dynamically, so the corresponding registers
need to be considered volatile. Affected registers are:

 - fuel gauge
 - battery status
 - battery interrupt
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/rn5t618.c

@@ -44,6 +44,9 @@ static bool rn5t618_volatile_reg(struct device *dev, unsigned int reg)
 	case RN5T618_INTMON:
 	case RN5T618_RTC_CTRL1 ... RN5T618_RTC_CTRL2:
 	case RN5T618_RTC_SECONDS ... RN5T618_RTC_YEAR:
+	case RN5T618_CHGSTATE:
+	case RN5T618_CHGCTRL_IRR ... RN5T618_CHGERR_MONI:
+	case RN5T618_CONTROL ... RN5T618_CC_AVEREG0:
 		return true;
 	default:
 		return false;