OMAP: McBSP: Change wakeup signals

Configure only XRDYEN and RRDYEN wakeup signals
in order to get better power consumption.

Signed-off-by: Eduardo Valentin <eduardo.valentin@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>