device-manager: drop superfluous create_pixel_displays_for_renderer call

commit 29e27637694eefc962d53333c729e6cac1c66518 tried to move
create_pixel_displays_for_renderer down a couple of lines, but it
inadvertently copied it instead of moved it.

This commit fixes that.

https://bugs.freedesktop.org/show_bug.cgi?id=104353