net/mlx5: remove Tx implementation

net/mlx5: remove Tx implementation

This patch removes the existing Tx datapath code
as preparation step before introducing the new
implementation. The following entities are being
removed:

- deprecated devargs support
- tx_burst() routines
- related PRM definitions
- SQ configuration code
- Tx routine selection code
- incompatible Tx completion code

The following devargs are deprecated and ignored:
- "txq_inline" is going to be converted to "txq_inline_max"
  for compatibility issue
- "tx_vec_en"
- "txqs_max_vec"
- "txq_mpw_hdr_dseg_en"
- "txq_max_inline_len" is going to be converted
  to "txq_inline_mpw" for compatibility issue

The deprecated devarg keys are recognized by PMD
and ignored/converted to the new ones in order not
to block device probing.

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>