bnx2x: increase inner ip id during encapsulated tso

57712/578xx devices during handling of encapsulated TSO can
properly increase ip id for only one ip header.
The patch selects inner header to be increased.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
CC: Eilon Greenstein <eilong@broadcom.com>
CC: Ariel Elior <ariele@broadcom.com>
CC: Maciej Zenczykowski <maze@google.com>
CC: Jesse Gross <jesse@nicira.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Tested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>