of: property: Add device link support for iommus, mboxes and io-channels

Add support for creating device links out of more DT properties.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20191105065000.50407-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>