Fix compilation breakage with tm6000

Randy Dunlap <randy.dunlap@oracle.com>  reported a breakage while compiling
drivers/staging/tm6000, due to this change:
    commit 1c1b78bee1a94f98deeb9c24b21c4812e191646c
    Author: Greg Kroah-Hartman <gregkh@suse.de>
    Date:   Thu Apr 29 15:46:07 2010 -0700

    USB: remove unused usb_buffer_alloc and usb_buffer_free macros

    Now that all callers are converted over, remove the compatibility
    functions and all is good.

As the function got renamed, the rename should also be applied at
tm6000.

Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/tm6000/tm6000-video.c

@@ -587,7 +587,7 @@ static void tm6000_uninit_isoc(struct tm6000_core *dev)
 			usb_kill_urb(urb);
 			usb_unlink_urb(urb);
 			if (dev->isoc_ctl.transfer_buffer[i]) {
-				usb_buffer_free(dev->udev,
+				usb_free_coherent(dev->udev,
 						urb->transfer_buffer_length,
 						dev->isoc_ctl.transfer_buffer[i],
 						urb->transfer_dma);
@@ -674,7 +674,7 @@ static int tm6000_prepare_isoc(struct tm6000_core *dev, unsigned int framesize)
 		}
 		dev->isoc_ctl.urb[i] = urb;
 
-		dev->isoc_ctl.transfer_buffer[i] = usb_buffer_alloc(dev->udev,
+		dev->isoc_ctl.transfer_buffer[i] = usb_alloc_coherent(dev->udev,
 			sb_size, GFP_KERNEL, &urb->transfer_dma);
 		if (!dev->isoc_ctl.transfer_buffer[i]) {
 			tm6000_err ("unable to allocate %i bytes for transfer"