Add support for devices using Enhanced Allocation entries instead of BARs.
This allows the kernel to parse the EA Extended Capability structure in PCI
config space and claim the BAR-equivalent resources.

See https://pcisig.com/sites/default/files/specification_documents/ECN_Enhanced_Allocation_23_Oct_2014_Final.pdf

[bhelgaas: add spec URL, s/pci_ea_set_flags/pci_ea_flags/, consolidate
declarations, print unknown property in hex to match spec]
Signed-off-by: NSean O. Stalley <sean.stalley@intel.com>
[david.daney@cavium.com: Add more support/checking for Entry Properties,
allow EA behind bridges, rewrite some error messages.]
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>