Avoid NULL for non-pointer

FreeBSD and OpenBSD define NULL as nullptr for C++11 or later.
freebsd/freebsd-src@c8ed04c
openbsd/src@6ecde74

Source/GmmLib/TranslationTable/GmmPageTableMgr.cpp:415:21: error: non-pointer operand type 'GMM_GFX_ADDRESS' (aka 'unsigned long') incompatible with nullptr
    return AuxTTObj ? AuxTTObj->GetL3Address() : NULL;
                    ^ ~~~~~~~~~~~~~~~~~~~~~~~~
Source/GmmLib/TranslationTable/GmmPageTableMgr.cpp:474:28: error: invalid operands to binary expression ('GMM_GFX_ADDRESS' (aka 'unsigned long') and 'nullptr_t')
    if(GetAuxL3TableAddr() == NULL)
       ~~~~~~~~~~~~~~~~~~~ ^  ~~~~

Author: jbeich

Source/GmmLib/TranslationTable/GmmPageTableMgr.cpp

@@ -412,7 +412,7 @@ GmmLib::GmmPageTableMgr::GmmPageTableMgr(GMM_DEVICE_CALLBACKS_INT *DeviceCB, uin
 /////////////////////////////////////////////////////////////////////////////////////
 GMM_GFX_ADDRESS GmmLib::GmmPageTableMgr::GetAuxL3TableAddr()
 {
-    return AuxTTObj ? AuxTTObj->GetL3Address() : NULL;
+    return AuxTTObj ? AuxTTObj->GetL3Address() : 0;
 }
 
 /////////////////////////////////////////////////////////////////////////////////////
@@ -471,7 +471,7 @@ GMM_STATUS GmmLib::GmmPageTableMgr::InitContextAuxTableRegister(HANDLE CmdQHandl
 /////////////////////////////////////////////////////////////////////////////////////
 GMM_STATUS GmmLib::GmmPageTableMgr::UpdateAuxTable(const GMM_DDI_UPDATEAUXTABLE *UpdateReq)
 {
-    if(GetAuxL3TableAddr() == NULL)
+    if(GetAuxL3TableAddr() == 0)
     {
         GMM_ASSERTDPF(0, "Invalid AuxTable update request, AuxTable is not initialized");
         return GMM_INVALIDPARAM;