Change wfd message for video only mirroring

Change wfd message for video only mirroring

Using this patch, 'wfd-audio-formats' parameter have none parameter for video only sink.

Basically, screen mirroring provides video & audio simultaneously.
This patch will make screen mirroring to provide Video only.

-When Video only mirroring mode, it doesn't make audio plugins.

If 'sink session mode' in 'mmfw_wfd_sink.ini' is set '2',
screen mirroring runs without audio(that is, video only mirroring)

Change-Id: I8d5fa9c6d6d9ac02868f3f87334b757104615e9e
Signed-off-by: Hyunsoo, Park <hance.park@samsung.com>