net/cnxk: avoid command copy from Tx queue

net/cnxk: avoid command copy from Tx queue

Tx command is prepared based on offloads enabled and stored in
Tx queue structure at tx_queue_setup phase.
In fastpath the command is copied from Tx queue to LMT line for
all the packets.
Since, the command contents are mostly constants we can move the
command preparation to fastpath and avoid accessing Tx queue
memory.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>