OSHMEM/free: suppressed coverity issue

- removed dead code

(cherry picked from master 4df8c1b)

Signed-off-by: Sergey Oblomov <sergeyo@mellanox.com>
Signed-off-by: Yossi Itigin <yosefe@mellanox.com>

oshmem/shmem/c/shmem_free.c

@@ -59,8 +59,6 @@ static inline void _shfree(void* ptr)
 
     if (ptr) {
         s = memheap_find_va(ptr);
-    } else {
-        s = NULL;
     }
 
     if (s && s->allocator) {