weston: change wl_output of virtual display.

weston: change wl_output of virtual display.

Bug-AGL : SPEC-2420

Currently, if remoting is enabled, the remote output
location is (0, 0) and the real DRM output is located
to the right of the remote output because the remote
output is registered before the real DRM output.

This patch is swapping both outputs as a short term
hack[1].

Now, this issue is being discussed about output layout
configuration in wayland community[2]

[reference]
[1] https://gitlab.freedesktop.org/wayland/weston/issues/246
[2] https://gitlab.freedesktop.org/wayland/weston/issues/165

Change-Id: Ia1265b6c2767f32754a2fd6507d1b6ebcb773464
Signed-off-by: Harunobu Kurokawa <harunobu.kurokawa.dn@renesas.com>