Make sure only to copy any actual data rather than the whole buffer,
when releasing the temporary buffer used for unaligned non-isochronous
transfers.

Compile-tested only.
Signed-off-by: NJohan Hovold <johan@kernel.org>
Tested-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>