ASoC: Don't use wm8994->control_data in wm8994_readable_register()

The field is no longer initialised so this will crash if running on
wm8958.

Reported-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org
1 file changed