ASoC: ux500: register controls to card instead of codec

Update mop500_ab8500_machine_init to register mop500_ab8500_ctrls as
card control instead of codec control, as it only contains
SOC_DAPM_PIN_SWITCH definitions.

Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>