bsc CBSP: introduce g_cbsp_msg_id and g_cbsp_ser_no

For each CBSP test, define one global set of CBSP msg id and serno for use by
that test.

Each CBSP test should use a distinct message id and serial nr, to not get mixed
up with previous state. But keeping those numbers manually is a confusing pain,
and as a reader it is hard to follow how these numbers change (if they do).

In f_cbsp_init_server(), require a preset of msg id and serno to be used in
that test, and from then on only use g_cbsp_msg_id and g_cbsp_ser_no instead of
magic numbers. If they change, write it out explicitly, making it easy to
follow what is expected to happen, and also making it easy to copy-paste code
snippets without having to manually adjust magic numbers.

Choice of numbers: pick a simpler scheme where both msg_id and ser_no share a
common "prefix" in the 1000s range, and for a ser_no add 500 to keep distinct
numbers (that avoid confusion when reading the logs):

test     prefix   msg_id   ser_no  next-ser_no
1        1000     1001     1501    1502
2        2000     2001     2501    2502
3        3000     3001     3501    3502
...

E.g. the first test has the prefix of 1000.
msg_id: 1001, ser_no: 1101.

Change-Id: I43ba196974614d1aea2b6055be2fe82059b38974
1 file changed