ASoC: kirkwood-i2s: fix pause handling some more

We still see the occasional timeout waiting for busy to clear.  As the
spec is contradictory, and we know that the current implementation
doesn't work, try an alternative interpretation from the spec.  This
one appears to work - I have yet to find any issue with it during my
testing over several months.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Mark Brown <broonie@linaro.org>