media: v4l: async: Rename v4l2_async_subdev as v4l2_async_connection

Rename v4l2_async_subdev as v4l2_async_connection, in order to
differentiate between the sub-devices and their connections: one
sub-device can have many connections but the V4L2 async framework has so
far allowed just a single one. Connections in this context will later
translate into either MC ancillary or data links.

This patch prepares changing that relation by changing existing users of
v4l2_async_subdev to switch to v4l2_async_connection. Async sub-devices
themselves will not be needed anymore

Additionally, __v4l2_async_nf_add_subdev() has been renamed
__v4l2_async_nf_add_connection().

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de> # imx6qp
Tested-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> # rcar + adv746x
Tested-by: Aishwarya Kothari <aishwarya.kothari@toradex.com> # Apalis i.MX6Q with TC358743
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> # Renesas RZ/G2L SMARC
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: platform: ti: avoid using 'videobuf' or 'video-buf'

These terms typically refer to the old version 1 videobuf framework.
It is confusing to use them for the vb2 framework, so reword these
comments.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: platform: rename am437x/ to ti/am437x/

As the end goal is to have platform drivers split by vendor,
rename am437x/ to ti/am437x/.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>