pcu: Verify LLC UI dummy frames are not appended at end of rlcmac DL block

LLC UI dummy frames are only to be sent alone in order to delay TBF
termination. Until recently (osmo-pcu.git
Ifae1a7b2b3dfad8df19585063088ba0df2749c8f), osmo-pcu was sending LLC UI
dummy frames instead of padding at RLCMAC layer, which made no sense.

Related: OS#4849
Change-Id: I7e0d9ed2475dbf989fbf932c8b83117ff5fb28fc
2 files changed