omap: McBSP: Remove unused audio macros in mcbsp.h

Some macros defined in mcbsp.h related to audio, which are never being used
is removed.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Charulatha V <charu@ti.com>
Cc: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: G, Manjunath Kondaiah <manjugk@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>