This does not fix a real bug, since virtual addresses
are currently indentical to physical ones.

Use virt_to_phys() for intparm interrupt parameter to
convert a 64-bit virtual address to the 32-bit physical
address, which is expected to be below 2GB.
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>