sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

mlx5ib: Implement support for enabling and disabling RoCE ECN.

RoCE is short for Remote direct memory access over Converged Ethernet.
ECN is short for Explicit Congestion Notification.

MFC after: 1 week
Reviewed by: kib
Sponsored by: Mellanox Technologies // NVIDIA Networking

Remove duplicate prototypes.

MFC after: 1 week
Sponsored by: Mellanox Technologies

Add support for explicit congestion notification, ECN, to mlx5ib(4).

ECN configuration and statistics is available through a set of sysctl(8)
nodes under sys.class.infiniband.mlx5_X.cong . The ECN configuration
nodes can also be used as loader tunables.

MFC after: 1 week
Sponsored by: Mellanox Technologies