ASoC: omap: Add .owner to struct snd_soc_card

Missed .owner of struct snd_soc_card will prevent the module from being
removed from underneath its users.

Reported-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@ti.com>