iio: imu: adis16550: fix swapped gyro/accel filter functions

iio: imu: adis16550: fix swapped gyro/accel filter functions

The low-pass filter handlers for IIO_ANGL_VEL and IIO_ACCEL call each
other's filter functions in both read_raw and write_raw. Swap them so
each channel type uses its correct filter accessor.

Fixes: bac4368fab62 ("iio: imu: adis16550: add adis16550 support")
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Acked-by: Robert Budai <robert.budai@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>