iio:imu:adis: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/adis.c

@@ -81,9 +81,11 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
 		adis->tx[9] = (value >> 24) & 0xff;
 		adis->tx[6] = ADIS_WRITE_REG(reg + 2);
 		adis->tx[7] = (value >> 16) & 0xff;
+		/* fall through */
 	case 2:
 		adis->tx[4] = ADIS_WRITE_REG(reg + 1);
 		adis->tx[5] = (value >> 8) & 0xff;
+		/* fall through */
 	case 1:
 		adis->tx[2] = ADIS_WRITE_REG(reg);
 		adis->tx[3] = value & 0xff;
@@ -167,6 +169,7 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
 		adis->tx[2] = ADIS_READ_REG(reg + 2);
 		adis->tx[3] = 0;
 		spi_message_add_tail(&xfers[1], &msg);
+		/* fall through */
 	case 2:
 		adis->tx[4] = ADIS_READ_REG(reg);
 		adis->tx[5] = 0;