ASoC: soc-ops: cleanup cppcheck warning at snd_soc_put_volsw_sx()

ASoC: soc-ops: cleanup cppcheck warning at snd_soc_put_volsw_sx()

This patch cleanups below cppcheck warning.

sound/soc/soc-ops.c:410:30: style: The scope of the variable 'val2' can be reduced. [variableScope]
 unsigned int val, val_mask, val2 = 0;
                             ^

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/874kc7w2a2.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>