usb: musc: Remove unused list 'buffers'

Remove the unused list head 'buffers' and the
'struct free_record' which is also unused below it.

To me it looks like this has always been unused, but I've
not dug into why.

Build test only.

Signed-off-by: "Dr. David Alan Gilbert" <linux@treblig.org>
Link: https://lore.kernel.org/r/20240504150315.77598-1-linux@treblig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Dr. David Alan Gilbert

drivers/usb/musb/musb_gadget.c

@@ -1156,15 +1156,6 @@ void musb_free_request(struct usb_ep *ep, struct usb_request *req)
 	kfree(request);
 }
 
-static LIST_HEAD(buffers);
-
-struct free_record {
-	struct list_head	list;
-	struct device		*dev;
-	unsigned		bytes;
-	dma_addr_t		dma;
-};
-
 /*
  * Context: controller locked, IRQs blocked.
  */