UCT/CUDA: Do not print host unregister error (use diag)

Calling cuMemHostUnregister does not produce an error when invoked from a
different context than the one it was originally registered in (or even
without an active context). However, it will fail if the context in which
the memory was allocated has been destroyed.

Author: brminich

src/uct/cuda/cuda_copy/cuda_copy_md.c

@@ -180,17 +180,11 @@ UCS_PROFILE_FUNC(ucs_status_t, uct_cuda_copy_mem_dereg,
                  (md, params),
                  uct_md_h md, const uct_md_mem_dereg_params_t *params)
 {
-    ucs_status_t status;
-
     UCT_MD_MEM_DEREG_CHECK_PARAMS(params, 0);
 
-    if (params->memh == &uct_cuda_dummy_memh) {
-        return UCS_OK;
-    }
-
-    status = UCT_CUDADRV_FUNC_LOG_ERR(cuMemHostUnregister((void*)params->memh));
-    if (status != UCS_OK) {
-        return status;
+    if (params->memh != &uct_cuda_dummy_memh) {
+        UCT_CUDADRV_FUNC(cuMemHostUnregister((void*)params->memh),
+                         UCS_LOG_LEVEL_DIAG);
     }
 
     return UCS_OK;