ASoC: simple-card: remove unused variable from simple_parse_of()

commit d9ffff69 ("ASoC: simple-card: Use snd_soc_of_parse_aux_devs()")
switched to use snd_soc_of_parse_aux_devs() on simple_parse_of().
Thus noone is using *top anymore. Let's cleanup unused variable.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87pmyxzs9w.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>