usb: gadget: function: sync f_uac1 ac header baInterfaceNr

f_uac1 audio control header descriptor default set
baInterfaceNr[]={1,2}, but usb gadget make a configuration descriptor
with more interfaces combination, it can not confirm f_uac1 function
linked first. So always keep baInterfaceNr[]={1,2} is correct, and it
is necessary to sync baInterfaceNr[] with usb_interface_id() value.

Signed-off-by: Liang Shengjun <liangshengjun@hisilicon.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>