PCI/ERR: Update error status after reset_link()

PCI/ERR: Update error status after reset_link()

Commit 79641351a173 ("PCI/ERR: Handle fatal error recovery") uses
reset_link() to recover from fatal errors.  But during fatal error
recovery, if the initial value of error status is PCI_ERS_RESULT_DISCONNECT
or PCI_ERS_RESULT_NO_AER_DRIVER then even after successful recovery (using
reset_link()) pcie_do_recovery() will report the recovery result as
failure.  Update the status of error after reset_link().

You can reproduce this issue by triggering a SW DPC using "DPC Software
Trigger" bit in "DPC Control Register".  You should see recovery failed
dmesg log as below:

  pcieport 0000:00:16.0: DPC: containment event, status:0x1f27 source:0x0000
  pcieport 0000:00:16.0: DPC: software trigger detected
  pci 0000:04:00.0: AER: can't recover (no error_detected callback)
  pcieport 0000:00:16.0: AER: device recovery failed

Fixes: 79641351a173 ("PCI/ERR: Handle fatal error recovery")
Link: https://lore.kernel.org/r/a255fcb3a3fdebcd90f84e08b555f1786eb8eba2.1585000084.git.sathyanarayanan.kuppuswamy@linux.intel.com
[bhelgaas: split pci_channel_io_frozen simplification to separate patch]
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>