iio: adc: stmpe-adc: Cleanup endian type of local variable

Nothing stops data being of type __be16, which fixes the warning:

CHECK   drivers/iio/adc/stmpe-adc.c
drivers/iio/adc/stmpe-adc.c:202:29: warning: cast to restricted __be16
drivers/iio/adc/stmpe-adc.c:202:29: warning: cast to restricted __be16
drivers/iio/adc/stmpe-adc.c:202:29: warning: cast to restricted __be16
drivers/iio/adc/stmpe-adc.c:202:29: warning: cast to restricted __be16
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: <philippe.schenker@toradex.com>

drivers/iio/adc/stmpe-adc.c

@@ -175,7 +175,7 @@ static int stmpe_read_raw(struct iio_dev *indio_dev,
 static irqreturn_t stmpe_adc_isr(int irq, void *dev_id)
 {
 	struct stmpe_adc *info = (struct stmpe_adc *)dev_id;
-	u16 data;
+	__be16 data;
 
 	if (info->channel <= STMPE_ADC_LAST_NR) {
 		int int_sta;