net/ena: fix Tx SQ free space assessment

net/ena: fix Tx SQ free space assessment

Before starting transmission of Tx burst, the driver checked the
available space in the sq and limited the number of packets for
transmission accordingly.
The calculation was incorrect for fragmented packets and potentially had
significantly limited the length of Tx bursts.

This patch removes the assessment and pushes packets to the sq as long
as the burst is not exhausted and space is available in the sq.

Correct evaluation of the required space isn't possible before the burst
because it depends on the number of segments of each packet.
This patch adds per-packet space evaluation for each packet before
attempting to process it. In case there is not enough queue space, the
burst will just stop without error.

Fixes: 2061fe41f212 ("net/ena: linearize Tx mbuf")
Cc: stable@dpdk.org
Signed-off-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Michal Krawczyk <mk@semihalf.com>