tcap_as_loadshare: Don't fill in PC from M3UA
If both calling and called_addr are not point codes then the compare in
tcap_trans_track_entry_find() will ignore them. It still matches on
otid/dtid.
Related: SYS#5423
Change-Id: I4f99fc87cd33ee3f2aad531710cc39a9b9c7e6d9
