[#2207] Re-ordered broken null check

STACK Output:
bug: anti-simplify
model: |
  %cmp33 = icmp eq %struct.RescGrpInfo** %rescGrpInfoHead, null, !dbg !1316
  -->  false
stack:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsGetRescQuota.cpp:350:0
ncore: 1
core:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsGetRescQuota.cpp:323:0
    - null pointer dereference