media: i2c: replace of_graph_get_next_endpoint()

From DT point of view, in general, drivers should be asking for a
specific port number because their function is fixed in the binding.

of_graph_get_next_endpoint() doesn't match to this concept.

Simply replace

	- of_graph_get_next_endpoint(xxx, NULL);
	+ of_graph_get_endpoint_by_regs(xxx, 0, -1);

Link: https://lore.kernel.org/r/20240202174941.GA310089-robh@kernel.org
Link: https://lore.kernel.org/r/9d1e99b0-892d-4a72-a9b3-886b8ed094b0@xs4all.nl


Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>