OSHMEM: spml ikrit: complete puts b4 memheap destruction

Force completion of all puts before deregestering memheap/bss memory

Fixes a possible race condition where put request completion callback
is called when request context is already cleared.

Change-Id: I7ed887ec0b03a66ce5d3076a7edcf64061f57370

oshmem/mca/spml/ikrit/spml_ikrit.c

@@ -662,6 +662,7 @@ int mca_spml_ikrit_deregister(sshmem_mkey_t *mkeys)
 {
     int i;
 
+    MCA_SPML_CALL(fence());
     if (!mkeys)
         return OSHMEM_SUCCESS;