x86/PCI: Infrastructure to maintain a list of FW-assigned BIOS BAR values

Commit 58c84eda introduced functionality to try and reinstate the
original BIOS BAR addresses of a PCI device when normal resource
assignment attempts fail.  To keep track of the BIOS BAR addresses,
struct pci_dev was augmented with an array to hold the BAR addresses
of the PCI device: 'resource_size_t fw_addr[DEVICE_COUNT_RESOURCE]'.

The reinstatement of BAR addresses is an uncommon event leaving the
'fw_addr' array unused under normal circumstances.  This functionality
is also currently architecture specific with an implementation limited
to x86.  As the use of struct pci_dev is so prevalent, having the
'fw_addr' array residing within such seems somewhat wasteful.

This patch introduces a stand alone data structure and interfacing
routines for maintaining a list of FW-assigned BIOS BAR value entries.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>