FROMGIT: 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>
(cherry-pick from commit 8e12257dead76131701c90a3555b0967727efc3f
 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git driver-core-next)
Change-Id: I035c27c805380c69110d274b24d81265883bc301