iio: health: max30102: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Notice that in this particular case, I placed the "fall through"
annotation at the bottom of the case, which is what GCC is expecting
to find.

Addresses-Coverity-ID: 1458342 ("Missing break in switch")
Addresses-Coverity-ID: 1458345 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/health/max30102.c

@@ -282,9 +282,11 @@ static int max30102_read_measurement(struct max30102_data *data,
 	switch (measurements) {
 	case 3:
 		MAX30102_COPY_DATA(2);
-	case 2: /* fall-through */
+		/* fall through */
+	case 2:
 		MAX30102_COPY_DATA(1);
-	case 1: /* fall-through */
+		/* fall through */
+	case 1:
 		MAX30102_COPY_DATA(0);
 		break;
 	default: