staging: unisys: iochannel.h add_phys_info needs u64 pfn

The pfn field in the channel is 64 bits, the parameter being passed
should be 64 bits as well.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>