ecore_x_2w: add pointer check

ecore_x_2w: add pointer check

To fix this build issue:
phone-0.6.63.25/lib/dialer/ph-dialer-view.c:1150:2:
     error: invalid use of void expression

And the code there is like this:
ecore_x_window_size_get(win, &win_width, NULL);

So the fix is, to check w and h to avoid when they're null.

And one more thing is to use (int *) to use the pointer correctly.