firmware: arm_scpi: mark scpi_get_sensor_value as static

scpi_get_sensor_value like other scpi operations needs to be static.
This patch marks it as static to be consistent with others.
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scpi.c

@@ -522,7 +522,7 @@ static int scpi_sensor_get_info(u16 sensor_id, struct scpi_sensor_info *info)
 	return ret;
 }
 
-int scpi_sensor_get_value(u16 sensor, u64 *val)
+static int scpi_sensor_get_value(u16 sensor, u64 *val)
 {
 	__le16 id = cpu_to_le16(sensor);
 	struct sensor_value buf;