net/ena: remove Tx mbuf linearization

net/ena: remove Tx mbuf linearization

The linearization of the mbuf isn't common practice for the PMD, as it
can expose it's capabilities to the upper layer using
rte_eth_dev_info_get().

Moreover, the rte_eth_tx_prepare() function should also verify if the
number of segments inside the mbuf isn't too high.

Because of those 2 circumstances, it may be safer to avoid modifying
mbuf on PMD's Tx side and remove linearization at all. Instead, add
verification of the number of segments to the eth_ena_prep_pkts().

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Artur Rojek <ar@semihalf.com>
Reviewed-by: Dawid Gorecki <dgr@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Shai Brandes <shaibran@amazon.com>