devlink: Add support for resource abstraction

Add support for hardware resource abstraction over devlink. Each resource
is identified via id, furthermore it contains information regarding its
size and its related sub resources. Each resource can also provide its
current occupancy.

In some cases the sizes of some resources can be changed, yet for those
changes to take place a hot driver reload may be needed. The reload
capability will be introduced in the next patch.

Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>