ecore_wl2: fix key down event called to often

ecore_wl2: fix key down event called to often

if many events are coming in, a release event can be skipped. if this happens
the timer continues with the new keycode. so if a new key pressed event
enter checks for the old timer and delete the timer if there is one.

If the timer kicks in and emits additional key down events dont call the
callback which gets called by wl, and emit the signal directly.