drivers/net: fix several Tx prepare functions

drivers/net: fix several Tx prepare functions

Since below commit, several tx_prep functions are broken, they fail to
pass supported Tx offload features check:
PKT_TX_IPVx must be set when any PKT_TX_L4 checksum is requested,
but these values are not present in the mask of supported Tx offloads
of several drivers that advertise PKT_TX_L4_MASK.
So any packet sent to those drivers with a L4 checksum request and
one of PKT_TX_IPVx bit set is rejected by the tx prepare function.

Fixes: 1037ed842c37 ("mbuf: fix Tx offload mask")
Cc: stable@dpdk.org
Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>