SWDEV-327967 - Fix Segmentation fault in hipFree

Queue creation and release fails during hipFree causing seg fault
if the null queue was not created until then and there is no
device memory left.

Change-Id: I118b86b58e777dac5415bc9ba0c4e23c986efa7d

hipamd/src/hip_memory.cpp

@@ -101,7 +101,10 @@ hipError_t ihipFree(void *ptr)
       }
     } else {
       // Wait on the device, associated with the current memory object
-      hip::getNullStream(memory_object->getContext())->finish();
+      amd::HostQueue* queue = hip::getNullStream(memory_object->getContext());
+      if (queue != nullptr) {
+        queue->finish();
+      }
       deviceID = hip::getDeviceID(memory_object->getContext());
     }
     hip::Stream::syncNonBlockingStreams(deviceID);