msg/async/rdma: define package sequence numbers macro

msg/async/rdma: define package sequence numbers macro

Refer to Doc: InfiniBandTM Architecture Specification Volume 1 Ver1.2.1
Section: 9.2 BASE TRANSPORT HEADER

bits  |31---------24 | 23-----------16 | 15----------8 | 7---------0 |
bytes |______________________________________________________________|
0 - 3 |____OpCode____|__|SE|M|Pad|Tver_|_________ Partition Key______|
4 - 7 |___Reserved___|______________Destination QP___________________|
8 -11 |A|Reserved 7__|________ PSN - Packet Sequence Number _________|

Signed-off-by: Changcheng Liu <changcheng.liu@aliyun.com>