net: Swap ver and type in pppoe_hdr

[ Upstream commit b1a5a34bd0b8767ea689e68f8ea513e9710b671e ]

Ver and type in pppoe_hdr should be swapped as defined by RFC2516
section-4.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>