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
Merge branch 'topic/oshmem_spml_ikrit_race'