Merge branch 'PCI-Add-and-use-constant-PCI_STATUS_ERROR_BITS-and-helper-pci_status_ge...

Merge branch 'PCI-Add-and-use-constant-PCI_STATUS_ERROR_BITS-and-helper-pci_status_get_and_clear_errors'

Heiner Kallweit says:

====================
PCI: Add and use constant PCI_STATUS_ERROR_BITS and helper pci_status_get_and_clear_errors

Several drivers have own definitions for this constant, so move it
to the PCI core. In addition in multiple places the following code
sequence is used:
1. Read PCI_STATUS
2. Mask out non-error bits
3. Action based on set error bits
4. Write back set error bits to clear them

As this is a repeated pattern, add a helper to the PCI core.

Most affected drivers are network drivers. But as it's about core
PCI functionality, I suppose the series should go through the PCI
tree.

v2:
- fix formal issue with cover letter
v3:
- fix dumb typo in patch 7
v4:
- add patches 1-3
- move new constant PCI_STATUS_ERROR_BITS to include/linux/pci.h
- small improvements in commit messages
====================

Signed-off-by: David S. Miller <davem@davemloft.net>