ecore_wl2: Remove just the flush from the idle handler

ecore_wl2: Remove just the flush from the idle handler

Flushing should be done where it's needed now, but we still
need the rest of the idle handler as something like mesa may
have dispatched its queue, which reads all the pending wayland
events.  In that case we have events to process but the fd will
not poll readable.

@fix T6250