iio: Fix endianness issue in ak8975_read_axis()

i2c_smbus_read_word_data() does host endian conversion already,
no need for le16_to_cpu()

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: Stable@vger.kernel.org