Remove hack that causes deadlock when waiting in eglSwapBuffers

This hack was added to work around the problem of calling
wl_display_iterate in two separate threads, but now that we are
are enforceing that wl_display_iterate can only be called in one thread
it now causes a deadlock when we are waiting in eglSwapBuffers for the
gui thread to actually call wl_display_iterate.

Change-Id: Id3153b184c191494838fc363380f7cae621ac64e
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>