ASoC: sh/fsi: Make one-bit bitfields unsigned

One-bit signed bitfields have two possible values: 0 and -1. This sometimes
leads to unexpected results (e.g. foo.bar = 1; foo.bar == 1 => false) which is
why it is recommended to make one-bit bitfields unsigned.

This fixes the following sparse warnings:
	sound/soc/sh/fsi.c:267:25: error: dubious one-bit signed bitfield
	sound/soc/sh/fsi.c:268:22: error: dubious one-bit signed bitfield
	sound/soc/sh/fsi.c:269:20: error: dubious one-bit signed bitfield
	sound/soc/sh/fsi.c:270:28: error: dubious one-bit signed bitfield
	sound/soc/sh/fsi.c:271:26: error: dubious one-bit signed bitfield
	sound/soc/sh/fsi.c:272:25: error: dubious one-bit signed bitfield

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>