of: property: fix typo in io-channels

commit 8f7e9179 upstream.

The property is io-channels and not io-channel. This was effectively
preventing the devlink creation.

Fixes: 8e12257d

 ("of: property: Add device link support for iommus, mboxes and io-channels")
Cc: stable@vger.kernel.org
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Saravana Kannan <saravanak@google.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240123-iio-backend-v7-1-1bff236b8693@analog.com
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>