soc: qcom: Add support for proxy consumers on of_devlink

A target may contain multiple defconfigs, but only one device-tree
configuration. Such a target may have device-drivers that are
only enabled in a particular defconfig, while disabled in the
others. For the kernel that boots up with disabled configuration,
since the device-tree node exists, the of_devlink logic expects
the driver to be probed, which is not possible. As a result, the
sync-state remains incomplete.

Hence, add support for a proxy consumer driver that shows a
proxy-presence of the main driver to satisfy the sync-state.

Change-Id: Ica8c2599fb66420c67e6a72e9b35e7afc0ae3220
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>