video: msm: wfd: Add support for multiple wfd device nodes

Creating another wfd device node for secure capture. Accordingly
changed the probe such that multiple wfd devices are supported.

Change-Id: I3f0db8c32c7a8aa8d6886c970c6a4cb9612e8857
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>