ASoC: soc-core: cleanup cppcheck warning at snd_soc_set_dmi_name()

This patch cleanups below cppcheck warning.

 const char *vendor, *product, *product_version, *board;
                                ^

sound/soc/soc-core.c:1721:33: style: The scope of the variable 'product_version' can be reduced. [variableScope]
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87wnp9yl6y.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>