ASoC: soc-pcm.c: use temporary variable at soc_get_playback_capture()

ASoC: soc-pcm.c: use temporary variable at soc_get_playback_capture()

soc_get_playback_capture() (A) returns number of substreams for
playback/capture (B).

(A)	static int soc_get_playback_capture(...,
(B)					int *playback, int *capture)
	{
		...
		for_each_xxx(...) {
			if (xxx)
				return -EINVAL;
=>			*playback = 1;
			...
=>			*capture = 1;
			...
		}
		...
	}

But, it is directly updating playback/capture which is the result of this
function even though it might be error. It should be updated in case of
succeed only. This patch updates it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/87ttvuzlqe.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>