OMAP: McBSP: use omap_device APIs to modify SYSCONFIG

McBSP2/3 in OMAP3 has sidetone feature which requires autoidle
to be disabled before starting the sidetone. Also SYSCONFIG
register has to be set with smart idle or no idle depending on the
dma op mode (threshold or element sync). For doing these operations
dynamically at runtime, omap_device APIs are used to modify SYSCONFIG register.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
[tony@atomide.com: updated to compile without omap_device idle calls]
Signed-off-by: Tony Lindgren <tony@atomide.com>