this patch adds device_slave_caps() callback as SiRF SoC sound drivers
depend on it.
Signed-off-by: NRongjun Ying <rongjun.ying@csr.com>
Signed-off-by: NBarry Song <Barry.Song@csr.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>