ASoC: usb: move the switch setting to more appropriate location

There is a delay between creation of sound card and creating of
corresponding steam. Currently we set the switch at the time of
creation of card. And later streams get created, so its more
optimal if we set the switch only after creating the stream.

Change-Id: Ic9f29d7a8dbcd32cde0097289ce6e1404a837372
Signed-off-by: Asish Bhattacharya <asishb@codeaurora.org>