Some or all are used by the Infiniband, MBIM, and RSVD dissectors; put
them into a common source file, with a header for them, and just include
the header in the dissectors.
Change-Id: I724f0c2232ba751ccbd491222af6f03bafd6d63c
Reviewed-on: https://code.wireshark.org/review/7182
Reviewed-by: Guy Harris <guy@alum.mit.edu>