bnxt_en: Add bnxt_en initial params table and register it.

Create initial devlink parameters table for bnxt_en.
Table consists of a permanent generic parameter.

enable_sriov - Enables Single-Root Input/Output Virtualization(SR-IOV)
characteristic of the device.

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