bnxt_en: Add missing devlink health reporters for VFs.

The VF driver also needs to create the health reporters since
VFs are also involved in firmware reset and recovery.  Modify
bnxt_dl_register() and bnxt_dl_unregister() so that they can
be called by the VFs to register/unregister devlink.  Only the PF
will register the devlink parameters.  With devlink registered,
we can now create the health reporters on the VFs.

Fixes: 6763c779 ("bnxt_en: Add new FW devlink_health_reporter")
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>