media: video-mux: Skip dangling endpoints

media: video-mux: Skip dangling endpoints

[ Upstream commit 95778c2d0979618e3349b1d2324ec282a5a6adbf ]

i.MX6 device tree include files contain dangling endpoints for the
board device tree writers' convenience. These are still included in
many existing device trees.
Treat dangling endpoints as non-existent to support them.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 612b385efb1e ("media: video-mux: Create media links in bound notifier")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>