media: Revert "media: dt-bindings: Document the Rockchip VPU bindings"

This reverts commit e4183d32.

The commit was picked by mistake, as the Rockchip VPU driver
is not ready for inclusion yet, and it's still under discussion.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>