media: v4l2-fwnode: Don't zero parts of struct v4l2_fwnode_endpoint anymore

Don't zero parts of the vep argument to v4l2_fwnode_endpoint_parse()
anymore as this can no longer be done while still supporting defaults on
multiple bus types.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>