[#2207] Removed unnecessary null check

STACK Output:
bug: anti-simplify
model: |
  %cmp189 = icmp ne %struct.DataObjInfo* %srcDataObjInfo.0, null, !dbg !4199
  -->  true
stack:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsDataObjRepl.cpp:896:0
ncore: 1
core:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsDataObjRepl.cpp:867:0
    - null pointer dereference