power: supply: ab8500: remove set but not used variables 'vbup33_vrtcn' and 'bup_vch_range'

Fixes gcc '-Wunused-but-set-variable' warnings:

drivers/power/supply/ab8500_charger.c:
 In function ab8500_charger_init_hw_registers:
drivers/power/supply/ab8500_charger.c:3013:24: warning:
 variable vbup33_vrtcn set but not used [-Wunused-but-set-variable]
drivers/power/supply/ab8500_charger.c:3013:5: warning:
 variable bup_vch_range set but not used [-Wunused-but-set-variable]

Fixes: 4c4268dc ("power: supply: ab8500: Drop AB8540/9540 support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/ab8500_charger.c

@@ -3011,7 +3011,6 @@ static int ab8500_charger_usb_get_property(struct power_supply *psy,
 static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 {
 	int ret = 0;
-	u8 bup_vch_range = 0, vbup33_vrtcn = 0;
 
 	/* Setup maximum charger current and voltage for ABB cut2.0 */
 	if (!is_ab8500_1p1_or_earlier(di->parent)) {
@@ -3112,12 +3111,6 @@ static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 		goto out;
 	}
 
-	/* Backup battery voltage and current */
-	if (di->bm->bkup_bat_v > BUP_VCH_SEL_3P1V)
-		bup_vch_range = BUP_VCH_RANGE;
-	if (di->bm->bkup_bat_v == BUP_VCH_SEL_3P3V)
-		vbup33_vrtcn = VBUP33_VRTCN;
-
 	ret = abx500_set_register_interruptible(di->dev,
 		AB8500_RTC,
 		AB8500_RTC_BACKUP_CHG_REG,