egl: ensure a render node is passed to _eglFindDevice()
_eglFindDevice() will fail if it's not provided a render node: the EGLDevice list only contains one entry per render node, plus the special software device. Passing a primary node for a display-only device will not work.
Closes: #10142 (closed)
cc @itoral @enunes @leandrohrb @emersion @daniels @apinheiro