compositor-drm: Reduce code duplication on drm_output_switch_mode()

Call drm_output_init_egl() instead of duplicating the gbm surface and
gl renderer state initialization code.

Note that this makes error handling a bit worse. Before, if we failed
to allocate a gbm surface we could still recover. Failing the renderer
state creation would lead to inconsisten state. Now we end up in
inconsistent state on both cases.
1 file changed