[IA64] SN: Correct ROM resource length for BIOS copy

On SN systems, when setting the IORESOURCE_ROM_BIOS_COPY resource flag,
the resource length should be set to the actual size of the ROM image
so that a call to pci_map_rom() returns the correct size.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>