iio: adis16480: Add debugfs_reg_access entry

BugLink: https://bugs.launchpad.net/bugs/1858489

[ Upstream commit 4c35b7a5 ]

The driver is defining debugfs entries by calling
`adis16480_debugfs_init()`. However, those entries are attached to the
iio_dev debugfs entry which won't exist if no debugfs_reg_access
callback is provided.

Fixes: 2f3abe6c ("iio:imu: Add support for the ADIS16480 and similar IMUs")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/iio/imu/adis16480.c

@@ -724,6 +724,7 @@ static const struct iio_info adis16480_info = {
 	.write_raw = &adis16480_write_raw,
 	.update_scan_mode = adis_update_scan_mode,
 	.driver_module = THIS_MODULE,
+	.debugfs_reg_access = adis_debugfs_reg_access,
 };
 
 static int adis16480_stop_device(struct iio_dev *indio_dev)