soundwire: Add bank switch routine

SoundWire supports two registers banks. So, program the alternate bank
with new configuration and then performs bank switch.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>