event: Remove double window type check
event: Remove double window type check

In glk_select() we checked the type of the window before flushing its
buffer, then in flush_window_buffer() we checked it again and returned
early. Remove the first type check for simpler code.

wmvanvliet/Chimara,wmvanvliet/Chimara,wmvanvliet/Chimara,wmvanvliet/Chimara,wmvanvliet/Chimara