bnxt_en: Read partno and serialno of the board from VPD

Store the part number and serial number information from VPD in
the bnxt structure. Follow up patch will add the support to display
the information via devlink command.

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>