pcu: Fix counter expectancies after LLC UI dummy frame fixes in PCU

Recent commit 7d0f9a0ec383fcfca934731bd6979b6be6629c90 in osmo-pcu.git
fixed situation where lots of unneeded LLC UI dummy frames where being
sent. As a result, osmo-pcu correctly counts less dl rlcmac payload
bytes being sent, so we must adjust our test expectancies.

Related: OS#4849
Change-Id: I01c34a0948094b17cc0d67e613cd9b756f78c372
1 file changed