BACKPORT: ALSA: usb-audio: Move configuration to prepare.

BACKPORT: ALSA: usb-audio: Move configuration to prepare.

Move interface and endpoint configuration from hw_params to prepare
callback.  During system suspend/resume when the USB device power isn't
cycled the interface and endpoint configuration need to be set before
audio playback can continue.  Resume involves another call to prepare
but not to hw_params, moving it here allows a playing stream to continue
after resume.

This is modified from the version going upstream as the endpoint rework
in 3.5 has changed all of these interfaces.  Same functionality however.

BUG=chrome-os-parnter:12822
TEST=suspend/resume while playing audio to USB speakers.

(Backported from 61a709504b079110cd5b12ea9a4590ffea687a5c)
Change-Id: Ie70d8c4c74014b877b2b6244c5accb81b6fb8d5c
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/33583
Reviewed-by: Chih-Chung Chang <chihchung@chromium.org>