ASoC: sh: rz-ssi: Make return type of rz_ssi_stream_is_valid() to bool

rz_ssi_stream_is_valid() never returns an int, it returns the result of
a condition which is either true or false.

While at it, drop "!!" as the expression is boolean.
Reported-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20220110094711.8574-5-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/rz-ssi.c

@@ -188,14 +188,14 @@ static inline bool rz_ssi_is_dma_enabled(struct rz_ssi_priv *ssi)
 	return (ssi->playback.dma_ch && (ssi->dma_rt || ssi->capture.dma_ch));
 }
 
-static int rz_ssi_stream_is_valid(struct rz_ssi_priv *ssi,
-				  struct rz_ssi_stream *strm)
+static bool rz_ssi_stream_is_valid(struct rz_ssi_priv *ssi,
+				   struct rz_ssi_stream *strm)
 {
 	unsigned long flags;
-	int ret;
+	bool ret;
 
 	spin_lock_irqsave(&ssi->lock, flags);
-	ret = !!(strm->substream && strm->substream->runtime);
+	ret = strm->substream && strm->substream->runtime;
 	spin_unlock_irqrestore(&ssi->lock, flags);
 
 	return ret;