bsc: fix encryption a5/4 missing in TC_*_a5_4

After removing a5/4 from the default config, it also needs to be
explicitly enabled for these two tests.

Fixes: 26a3db ("bsc: change encryption a5 via VTY where needed")
Change-Id: Ibe00edb096f94b500869c46a39a694a73133c716
1 file changed