usb: gadget: f_uac2: Fix incorrect setting of bNumEndpoints

Currently afunc_bind sets std_ac_if_desc.bNumEndpoints to 1 if
controls (mute/volume) are enabled. During next afunc_bind call,
bNumEndpoints would be unchanged and incorrectly set to 1 even
if the controls aren't enabled.

Fix this by resetting the value of bNumEndpoints to 0 on every
afunc_bind call.

Fixes: eaf6cbe09920 ("usb: gadget: f_uac2: add volume and mute support")
Cc: stable <[e-mail]>
Signed-off-by: Prashanth K <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/function/f_uac2.c

···
 		uac2->as_in_alt = 0;
 	}
 
+	std_ac_if_desc.bNumEndpoints = 0;
 	if (FUOUT_EN(uac2_opts) || FUIN_EN(uac2_opts)) {
 		uac2->int_ep = usb_ep_autoconfig(gadget, &fs_ep_int_desc);
 		if (!uac2->int_ep) {