PIDL (DCERPC): fix Assigned value is garbage or undefined found by Clang Analyzer

packet-dcerpc-dnsserver.c:1002:12: warning: Assigned value is garbage or undefined
packet-dcerpc-frstrans.c:1137:12: warning: Assigned value is garbage or undefined
packet-dcerpc-lsa.c:6345:12: warning: Assigned value is garbage or undefined
packet-dcerpc-nspi.c:7805:12: warning: Assigned value is garbage or undefined
packet-dcerpc-dfs.c:3245:11: warning: Function call argument is an uninitialized value
packet-dcerpc-dfs.c:3245:9: warning: 'level' may be used uninitialized in this function [-Wmaybe-uninitialized]

Change-Id: Ife6a2f565ae215535d0e3d72ef50800114240e3f
Reviewed-on: https://code.wireshark.org/review/4478
Reviewed-by: Evan Huus <eapache@gmail.com>