Fix following warning:
WARNING: vmlinux.o(.text+0x11ec01a): Section mismatch in reference from the function setup_card() to the function .devinit.text:snd_usb_caiaq_control_init()
setup_card() are only used by init_card().
init_card() are only used by snd_probe()
snd_probe() are used for the .probe parameter in usb_driver.probe