devlink: extend devlink_trap_report() to accept cookie and pass

Add cookie argument to devlink_trap_report() allowing driver to pass in
the user cookie. Pass on the cookie down to drop monitor code.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>