Fix typo in staging/src/.../wait_test.go

Signed-off-by: he.qingguo <he.qingguo@zte.com.cn>

staging/src/k8s.io/apimachinery/pkg/util/wait/wait_test.go

@@ -692,7 +692,7 @@ func TestContextForChannel(t *testing.T) {
 	select {
 	case <-done:
 	case <-time.After(ForeverTestTimeout):
-		t.Errorf("unexepcted timeout waiting for parent to cancel child contexts")
+		t.Errorf("unexpected timeout waiting for parent to cancel child contexts")
 	}
 }