ASoC: rsnd: cleanup ppcheck warning for cmd.c

ASoC: rsnd: cleanup ppcheck warning for cmd.c

This patch cleanups below ppcheck warning.

sound/soc/sh/rcar/cmd.c:46:20: style: The scope of the variable 'src' can be reduced. [variableScope]
  struct rsnd_mod *src;
                   ^
sound/soc/sh/rcar/cmd.c:47:27: style: The scope of the variable 'tio' can be reduced. [variableScope]
  struct rsnd_dai_stream *tio;
                          ^
sound/soc/sh/rcar/cmd.c:145:13: style: The scope of the variable 'ret' can be reduced. [variableScope]
 int i, nr, ret;
            ^

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87h7m1ro28.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>