ASoC: rsnd: tidyup void* cast for 64bit compiler

64bit compiler indicates this without this patch

linux/sound/soc/sh/rcar/core.c: In function 'rsnd_probe':
linux/sound/soc/sh/rcar/core.c:1002:16: warning: cast from pointer to\
     integer of different size [-Wpointer-to-int-cast]

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>