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/storage/usb.c b/drivers/usb/storage/usb.c
index c54a370..e2798ef 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -414,7 +414,7 @@
 		return -ENOMEM;
 	}
 
-	us->iobuf = usb_buffer_alloc(us->pusb_dev, US_IOBUF_SIZE,
+	us->iobuf = usb_alloc_coherent(us->pusb_dev, US_IOBUF_SIZE,
 			GFP_KERNEL, &us->iobuf_dma);
 	if (!us->iobuf) {
 		US_DEBUGP("I/O buffer allocation failed\n");
@@ -758,7 +758,7 @@
 
 	/* Free the buffers */
 	kfree(us->cr);
-	usb_buffer_free(us->pusb_dev, US_IOBUF_SIZE, us->iobuf, us->iobuf_dma);
+	usb_free_coherent(us->pusb_dev, US_IOBUF_SIZE, us->iobuf, us->iobuf_dma);
 
 	/* Remove our private data from the interface */
 	usb_set_intfdata(us->pusb_intf, NULL);