drivers/misc/apds9802als.c: fix signedness bug

i2c_smbus_read_byte_data() may return negative error code.  This is not
seen to als_sensing_range_store() as the result is stored in unsigned int.

Made it signed.
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Cc: Hong Liu <hong.liu@intel.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Anantha Narayanan <anantha.narayanan@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/apds9802als.c

@@ -123,7 +123,7 @@ static ssize_t als_sensing_range_store(struct device *dev,
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct als_data *data = i2c_get_clientdata(client);
-	unsigned int ret_val;
+	int ret_val;
 	unsigned long val;
 
 	if (strict_strtoul(buf, 10, &val))