Add command line parameter to set SL for pingpong examples

Add a --sl/-l command line parameter for the pingpong examples to set
the SL of the QP/AH.  This can be used to test a QoS setup.

Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
8 files changed