Commit 976e8f67 ("x86: asm/io.h: unify
virt_to_phys/phys_to_virt") changed the return of virt_to_phys from long
to phys_addr_t which is unsigned long long on a PAE platform.

So, I could suggest a fix below since isa addresses may never be above
32 bits.
Signed-off-by: NIngo Molnar <mingo@elte.hu>