pci: Add SR-IOV convenience functions and macros

Add and export pci_num_vf to allow other subsystems to determine how many
virtual function devices are associated with an SR-IOV physical function
device.
Add macros dev_is_pci, dev_is_ps, and dev_num_vf to make it easier for
non-PCI specific code to determine SR-IOV capabilities.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>