devlink: Add support for resource/dpipe relation

devlink: Add support for resource/dpipe relation

Dpipe - Each dpipe table can have one resource which is mapped to it.
The resource is presented via its full path. Furthermore, the number
of units consumed by single table entry is presented.

Resource - Each resource presents the dpipe tables that use it.

Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>