net/bnxt: add initial Tx code

net/bnxt: add initial Tx code

Initial implementation of tx_pkt_burst for transmit.
bnxt_xmit_pkts() is the top level function that is called during Tx.

bnxt_handle_tx_cp() is used to check and process the Tx completions
generated for the Tx Buffer Descriptors sent by the hardware.

This patch also adds code to allocate rings in the hardware.
For each Tx queue allocated in the PMD driver, a corresponding ring
in hardware will be created. Every time a Tx request is initiated
via the bnxt_xmit_pkts() call, a Buffer Descriptor is created and
is sent to the hardware via the associated Tx ring.

On completing the Tx operation, the hardware will generates the status
in the form of a completion. This completion is processed by the
bnxt_handle_tx_cp() function.

Functions like bnxt_init_tx_ring_struct() and bnxt_init_one_tx_ring()
are used to initialize various members of the structure before
starting Tx operations.

Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Signed-off-by: Stephen Hurd <stephen.hurd@broadcom.com>
Reviewed-by: David Christensen <david.christensen@broadcom.com>