Introduce and use osmo-bts-trx VTY cmd max_trxd_version on sysmocell-5K

Force TRXDv0 when using sysmocell-5k as a TRX, since its implementation
(different than osmo-trx) doesn't support higher versions. Furthermore,
it will crash upon receival of SETFORMAT string. By forcing maximum TRXD
version to 0, osmo-bts-trx won't sent any SETFORMAT message since 0 is
the initial version to use.

Depends: osmo-bts.git I5eb1fdc002f9d7f4acf475356d8fc998dc8f6326
Related: OS#4006
Change-Id: Ic95c38d91dba354ae64c5edbfcea3fbbf34a7de3
3 files changed