MFC r270212,r270332:

This helps reduce the diff in pci(4) between head and stable/10 to help pave
the way for bringing in IOV/nv(9) more cleanly

Differential Revision: https://reviews.freebsd.org/D4728
Relnotes: yes
Reviewed by: hselasky (ofed piece), royger (overall change)
Sponsored by: EMC / Isilon Storage Division

r270212 (by royger):

pci: make MSI(-X) enable and disable methods of the PCI bus

Make the functions pci_disable_msi, pci_enable_msi and pci_enable_msix
methods of the newbus PCI bus. This code should not include any
functional change.

Sponsored by: Citrix Systems R&D
Reviewed by: imp, jhb
Differential Revision: https://reviews.freebsd.org/D354

dev/pci/pci.c:

• Convert the mentioned functions to newbus methods.
• Fix the callers of the converted functions.

sys/dev/pci/pci_private.h:
dev/pci/pci_if.m:

• Declare the new methods.

dev/pci/pcivar.h:

• Add helpers to call the newbus methods.

ofed/include/linux/pci.h:

• Add define to prevent the ofed version of pci_enable_msix from clashing with the FreeBSD native version.

r270332 (by royger):

pci: add a new pci_child_added newbus method.

This is needed so when running under Xen the calls to pci_child_added
can be intercepted and a custom Xen method can be used to register
those devices with Xen. This should not include any functional
change, since the Xen implementation will be added in a following
patch and the native implementation is a noop.

Sponsored by: Citrix Systems R&D
Reviewed by: jhb

dev/pci/pci.c:
dev/pci/pci_if.m:
dev/pci/pci_private.h:
dev/pci/pcivar.h:

• Add the pci_child_added newbus method.