usb: gadget: f_uac2: fix error handling at afunc_bind

The current error handling flow uses incorrect goto label, fix it

Cc: <stable@vger.kernel.org>
Fixes: d12a8727 ("usb: gadget: function: Remove
	redundant usb_free_all_descriptors")
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>