ASoC: siu: Fix build error by a wrong const prefix

ASoC: siu: Fix build error by a wrong const prefix

A const prefix was put wrongly in the middle at the code refactoring
commit 1413efcd8917 ("ASoC: sh: siu_pcm: remove snd_pcm_ops"), which
leads to a build error as:
  sound/soc/sh/siu_pcm.c:546:8: error: expected '{' before 'const'

Also, another inconsistency is that the declaration of siu_component
misses the const prefix.

This patch corrects both failures.

Fixes: 1413efcd8917 ("ASoC: sh: siu_pcm: remove snd_pcm_ops")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20210126154702.3974-1-tiwai@suse.de
Signed-off-by: Mark Brown <broonie@kernel.org>