Fixed the resolution doesn't match LCD resolution when using Systeminfo DISPLAY attribute.

BUG=XWALK-1927
wayland is out of my knowledge, from the doc, seems two modes available: preferred and current. My question is:
Does the callback `display_handle_mode` will be call again and again? Then in some state, the mode is current, then we can get the size correctly. Otherwise, if the callback won't called only once and it is under preferred mode,  the size won't be set anymore.