Revert "Drivers: hv: ring_buffer: count on wrap around mappings in get_next_pkt_raw()"

To deal with the merge conflict between net-next and char-misc trees,
revert commit bb08d431

 from char-misc tree. This commit can be rebased
and applied once net-next picks up char-misc changes.

Here is the commit log of the reverted patch:
"With wrap around mappings in place we can always provide drivers with
direct links to packets on the ring buffer, even when they wrap around.
Do the required updates to get_next_pkt_raw()/put_pkt_raw()"

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>