devlink: document devlink info versions reported by bnxt_en driver

Add the set of info versions reported by bnxt_en driver, including
a description of what the version represents, and what modes (fixed,
running, stored) it reports.

v2: Use fw.psid.

Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>