iio: adc: ina2xx: Fix incorrect report of data endianness to userspace.

This was extracted from a reposting of the driver after it had been applied
to the IIO tree.  I have fast tracked it as the driver will be in 4.5 and
it would be nice to fix this trivial issue before it is.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/ina2xx-adc.c

@@ -400,7 +400,7 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
 		.sign = 'u', \
 		.realbits = 16, \
 		.storagebits = 16, \
-		.endianness = IIO_LE, \
+		.endianness = IIO_CPU, \
 	} \
 }