power: supply: sbs-battery: Fix a signedness bug in sbs_get_battery_capacity()

The "mode" variable is an enum and in this context GCC treats it as an
unsigned int so the error handling is never triggered.

Fixes: 51d07566 ("bq20z75: Add support for charge properties")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/sbs-battery.c

@@ -556,7 +556,7 @@ static int sbs_get_battery_capacity(struct i2c_client *client,
 		mode = CAPACITY_MODE_AMPS;
 
 	mode = sbs_set_capacity_mode(client, mode);
-	if (mode < 0)
+	if ((int)mode < 0)
 		return mode;
 
 	ret = sbs_read_word_data(client, sbs_data[reg_offset].addr);