btl/uct: downgrade endpoing lock from recursive

Recursive locks are not needed for the endpoint lock. This commit modifies the
lock to be opal_mutex_t.

Author: hjelmn

opal/mca/btl/uct/btl_uct_endpoint.c

@@ -24,7 +24,7 @@ static void mca_btl_uct_endpoint_construct(mca_btl_uct_endpoint_t *endpoint)
     memset(endpoint->uct_eps, 0,
            sizeof(endpoint->uct_eps[0]) * mca_btl_uct_component.num_contexts_per_module);
     endpoint->conn_ep = NULL;
-    OBJ_CONSTRUCT(&endpoint->ep_lock, opal_recursive_mutex_t);
+    OBJ_CONSTRUCT(&endpoint->ep_lock, opal_mutex_t);
 }
 
 static void mca_btl_uct_endpoint_destruct(mca_btl_uct_endpoint_t *endpoint)

opal/mca/btl/uct/btl_uct_types.h

@@ -288,7 +288,7 @@ struct mca_btl_base_endpoint_t {
     opal_proc_t *ep_proc;
 
     /** mutex to protect this structure */
-    opal_recursive_mutex_t ep_lock;
+    opal_mutex_t ep_lock;
 
     /** cached connection endpoint */
     mca_btl_uct_connection_ep_t *conn_ep;