ALSA: usb-audio: Don't set altsetting before initializing sample rate

Setting the active altsetting at changing sample rate seems
unrecommended.  The host should deselect the altsetting at first
before that, then select it again.

Tested-by: Keith Milner <kamilner@superlative.org>
Tested-by: Dylan Robinson <dylan_robinson@motu.com>
Link: https://lore.kernel.org/r/20201123085347.19667-18-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>