tipc: add media get/dump to new netlink api

tipc: add media get/dump to new netlink api

Add TIPC_NL_MEDIA_GET command to the new tipc netlink API.

This command supports dumping all information about all defined
media as well as getting all information about a specific media.

The information about a media includes name and link properties.

Netlink logical layout of media get response message:
-> media
    -> name
    -> link properties
        -> tolerance
        -> priority
        -> window

Signed-off-by: Richard Alpe <[email protected]>
Reviewed-by: Erik Hugne <[email protected]>
Reviewed-by: Jon Maloy <[email protected]>
Acked-by: Ying Xue <[email protected]>
Signed-off-by: David S. Miller <[email protected]>