power: supply: ab8500_charger: Fix an error handling path

'ret' is know to be 0 at this point, because it has not been updated by the
the previous call to 'abx500_mask_and_set_register_interruptible()'.

Fix it by updating 'ret' before checking if an error occurred.

Fixes: 84edbeeab67c ("ab8500-charger: AB8500 charger driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

drivers/power/supply/ab8500_charger.c

@@ -3218,7 +3218,7 @@ static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 	}
 
 	/* Enable backup battery charging */
-	abx500_mask_and_set_register_interruptible(di->dev,
+	ret = abx500_mask_and_set_register_interruptible(di->dev,
 		AB8500_RTC, AB8500_RTC_CTRL_REG,
 		RTC_BUP_CH_ENA, RTC_BUP_CH_ENA);
 	if (ret < 0)