bnxt_en: Fix VF PCIe link speed and width logic.

PCIE PCIE_EP_REG_LINK_STATUS_CONTROL register is only defined in PF
config space, so we must read it from the PF.

Fixes: 90c4f788 ("bnxt_en: Report PCIe link speed and width during driver load")
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>