bnxt_en: Fix PCI AER error recovery flow

When a PCI error is detected the PCI state could be corrupt, save
the PCI state after initialization and restore it after the slot
reset.

Fixes: 6316ea6d

 ("bnxt_en: Enable AER support.")
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>