net/mlx5: create and destroy eCPRI flex parser

net/mlx5: create and destroy eCPRI flex parser

eCPRI protocol has unified format layout for the variants, over
ETH layer (including .1Q) and UDP layer.

The common header of the message has 4 bytes fixed length, and the
message payload layers are different based on the type field. Now
only type #0, #2 and #5 will be supported, and 2 bytes are needed.

When creating the flex parser, the header will be extended to 8
bytes and 2 DW samples are needed. The 1st DW starts from offset 0
and will be used for the type field of the common header. The 2nd
DW starts from offset 4 and will be used for the physical channel
ID, real-time control ID or measurement ID fields.

The parser will be created once a flow with eCPRI item is observed
for the first time. After creating, it will remain in the system
and HW until the device is stopped. Right now, there is no need to
destroy the eCPRI flex parser after the last flow with eCPRI item
is destroyed. This is to get rid of the alternate states of creating
and destroying eCPRI flex parser with a single eCPRI flow.

Signed-off-by: Bing Zhao <bingz@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>