net: thunderx: Fix for issues with multiple CQEs posted for a TSO packet

On ThunderX 88xx pass 2.x chips when TSO is offloaded to HW,
HW posts a CQE for every TSO segment transmitted. Current code
does handles this, but is prone to issues when segment sizes are
small resulting in SW processing too many CQEs and also at times
frees a SKB which is not yet transmitted.

This patch handles the errata in a different way and eliminates issues
with earlier approach, TSO packet is submitted to HW with post_cqe=0,
so that no CQE is posted upon completion of transmission of TSO packet
but a additional HDR + IMMEDIATE descriptors are added to SQ due to
which a CQE is posted and will have required info to be used while
cleanup in napi. This way only one CQE is posted for a TSO packet.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>