iio: cros_ec_accel_legacy: Refactor code in cros_ec_accel_legacy_probe

Refactor some code in order to fix both the technical implementation
and the following warnings:

drivers/iio/accel/cros_ec_accel_legacy.c: In function ‘cros_ec_accel_legacy_probe’:
drivers/iio/accel/cros_ec_accel_legacy.c:387:36: warning: this statement may fall through [-Wimplicit-fallthrough=]
    ec_accel_channels[X].scan_index = Y;
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
drivers/iio/accel/cros_ec_accel_legacy.c:388:3: note: here
   case Y:
   ^~~~
drivers/iio/accel/cros_ec_accel_legacy.c:389:36: warning: this statement may fall through [-Wimplicit-fallthrough=]
    ec_accel_channels[Y].scan_index = X;
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
drivers/iio/accel/cros_ec_accel_legacy.c:390:3: note: here
   case Z:
   ^~~~

Notice that neither the for loop nor the switch statement is needed.
Also, "state->sign[Y] = 1" should be unconditional.

This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/cros_ec_accel_legacy.c

@@ -353,7 +353,7 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
 	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
 	struct iio_dev *indio_dev;
 	struct cros_ec_accel_legacy_state *state;
-	int ret, i;
+	int ret;
 
 	if (!ec || !ec->ec_dev) {
 		dev_warn(&pdev->dev, "No EC device found.\n");
@@ -381,20 +381,17 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
 	 * Present the channel using HTML5 standard:
 	 * need to invert X and Y and invert some lid axis.
 	 */
-	for (i = X ; i < MAX_AXIS; i++) {
-		switch (i) {
-		case X:
-			ec_accel_channels[X].scan_index = Y;
-		case Y:
-			ec_accel_channels[Y].scan_index = X;
-		case Z:
-			ec_accel_channels[Z].scan_index = Z;
-		}
-		if (state->sensor_num == MOTIONSENSE_LOC_LID && i != Y)
-			state->sign[i] = -1;
-		else
-			state->sign[i] = 1;
-	}
+	ec_accel_channels[X].scan_index = Y;
+	ec_accel_channels[Y].scan_index = X;
+	ec_accel_channels[Z].scan_index = Z;
+
+	state->sign[Y] = 1;
+
+	if (state->sensor_num == MOTIONSENSE_LOC_LID)
+		state->sign[X] = state->sign[Z] = -1;
+	else
+		state->sign[X] = state->sign[Z] = 1;
+
 	indio_dev->num_channels = ARRAY_SIZE(ec_accel_channels);
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->info = &cros_ec_accel_legacy_info;