intel_sst: ignore IRQ when suspended

The irq for audio is shared, so when device is supended driver should
not the read register and ignore the interrupt.

This patch ignores interrupts when device is suspended.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Ramesh Babu K V <ramesh.babu@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>