Convert pa_dev->hpa from an unsigned long to a struct resource.
Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>

Fix up users of ->hpa to use ->hpa.start instead.
Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>