OMAP: ASoC: Fix spinlock misuse in omap-pcm.c

omap_pcm_trigger is called also in interrupt context so CPU flags must
be restored when returning.

Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com>
Acked-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>