ALSA: usb-audio: Resume mixer values properly

Implement reset_resume callback so that the mixer values are properly
restored.  Still no boot quirks are called, so it might not work well
on some devices.

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

diff --cc sound/usb/card.c
Simple merge

diff --cc sound/usb/mixer.c
Simple merge

diff --cc sound/usb/mixer.h
Simple merge