net/mlx5: create rearm queue for packet pacing

net/mlx5: create rearm queue for packet pacing

The dedicated Rearm Queue is needed to fire the work requests to
the Clock Queue in realtime. The Clock Queue should never stop,
otherwise the clock synchronization might be broken and packet
send scheduling would fail. The Rearm Queue uses cross channel
SEND_EN/WAIT operations to provides the requests to the
Clock Queue in robust way.

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>