usb gadget stack: remove usb_ep_*_buffer(), part 1

Remove usb_ep_{alloc,free}_buffer() calls, for small dma-coherent buffers.
This patch just removes the interface and its users; later patches will
remove controller driver support.

  - This interface is invariably not implemented correctly in the
    controller drivers (e.g. using dma pools, a mechanism which
    post-dates the interface by several years).

  - At this point no gadget driver really *needs* to use it.  In
    current kernels, any driver that needs such a mechanism could
    allocate a dma pool themselves.

Removing this interface is thus a simplification and improvement.

Note that the gmidi.c driver had a bug in this area; fixed.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/gmidi.c b/drivers/usb/gadget/gmidi.c
index d08a8d0..1c5aa49 100644
--- a/drivers/usb/gadget/gmidi.c
+++ b/drivers/usb/gadget/gmidi.c
@@ -1248,17 +1248,11 @@
 	tasklet_init(&dev->tasklet, gmidi_in_tasklet, (unsigned long)dev);
 
 	/* preallocate control response and buffer */
-	dev->req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
+	dev->req = alloc_ep_req(gadget->ep0, USB_BUFSIZ);
 	if (!dev->req) {
 		err = -ENOMEM;
 		goto fail;
 	}
-	dev->req->buf = usb_ep_alloc_buffer(gadget->ep0, USB_BUFSIZ,
-				&dev->req->dma, GFP_KERNEL);
-	if (!dev->req->buf) {
-		err = -ENOMEM;
-		goto fail;
-	}
 
 	dev->req->complete = gmidi_setup_complete;