ASoC: rsnd: cleanup ppcheck warning for adg.c

ASoC: rsnd: cleanup ppcheck warning for adg.c

This patch cleanups below ppcheck warning.

sound/soc/sh/rcar/adg.c:67:9: style: The scope of the variable 'ratio' can be reduced. [variableScope]
 int i, ratio;
        ^
sound/soc/sh/rcar/adg.c:114:6: style: The scope of the variable 'idx' can be reduced. [variableScope]
 int idx, sel, div, step;
     ^
sound/soc/sh/rcar/adg.c:114:21: style: The scope of the variable 'step' can be reduced. [variableScope]
 int idx, sel, div, step;
                    ^
sound/soc/sh/rcar/adg.c:397:14: style: The scope of the variable 'clk' can be reduced. [variableScope]
 struct clk *clk;
             ^

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87ft1lro24.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>