fix msc_vlr tests after libosmocore uses localtime for SMS

libosmocore change-id I4efdb1eaae43aced33961b64d4f14b0040321c10 changes the
gsm340_gen_scts() from gmtime to localtime, meaning that by feeding a mere zero
as timestamp, we get different results depending on the local machine's
timezone setting. Instead of calling gsm340_gen_scts() with zero, simply write
a bunch of bytes as time so that the tests get identical SMS bytes every time.

Change-Id: I8a50e8963dce80609749571b61fc6ffe1c54660c
1 file changed