ASoC: fsi: fixup compile warning

This patch fixup below warning

${linux}/sound/soc/sh/fsi.c:442:3:\
 warning: passing argument 1 of '__fsi_reg_read' makes pointer\
 from integer without a cast
${linux}/sound/soc/sh/fsi.c:517:3: \
 warning: passing argument 1 of '__fsi_reg_write' makes pointer\
 from integer without a cast
${linux}/sound/soc/sh/fsi.c:663:3: \
 warning: passing argument 1 of '__fsi_reg_mask_set' makes pointer\
 from integer without a cast

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