USB: rename usb_buffer_alloc() and usb_buffer_free() users

For more clearance what the functions actually do,

  usb_buffer_alloc() is renamed to usb_alloc_coherent()
  usb_buffer_free()  is renamed to usb_free_coherent()

They should only be used in code which really needs DMA coherency.

All call sites have been changed accordingly, except for staging
drivers.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Pedro Ribeiro <pedrib@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 6152278..d110588 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -387,8 +387,8 @@
 	}
 
 	/* free up our allocated buffer */
-	usb_buffer_free(urb->dev, urb->transfer_buffer_length,
-			urb->transfer_buffer, urb->transfer_dma);
+	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+			  urb->transfer_buffer, urb->transfer_dma);
 	up(&dev->limit_sem);
 }
 
@@ -442,8 +442,8 @@
 		goto error;
 	}
 
-	buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL,
-			       &urb->transfer_dma);
+	buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
+				 &urb->transfer_dma);
 	if (!buf) {
 		retval = -ENOMEM;
 		goto error;
@@ -491,7 +491,7 @@
 	usb_unanchor_urb(urb);
 error:
 	if (urb) {
-		usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
+		usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
 		usb_free_urb(urb);
 	}
 	up(&dev->limit_sem);