media: ti-vpe: cal: Use of_graph_get_endpoint_by_regs() to parse OF

Replace the manual of_get_next_port() and of_get_next_endpoint()
implementations and the corresponding logic in the caller with a call to
of_graph_get_endpoint_by_regs(). This greatly simplifies OF parsing.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>