ASoC: kirkwood-i2s: fix RECCTL masking

Since we wish to disable capture inputs for some formats, we need to
ensure that we clear the enable bits in our cached record control
register.  This seems to have been missed, resulting in the register
only accumulating enable bits.

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>