rsocket: Merge usage of wr_id between stream and datagram svcs

The rsocket data streaming and datagram services use different
formats for the wr_id.  Although some differences are needed,
we can make them more similar.  This will be useful when the
wr_id is used for iwarp support, plus eliminates use of wr_id
bits that aren't actually needed.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>