[IA64] Fix of C/S 10529:4260eb8c08740de0000081c61a6237ffcb95b2d5 for IA64.

[IA64] Fix of C/S 10529:4260eb8c08740de0000081c61a6237ffcb95b2d5 for IA64.
When page is zapped from a domain, the page referenced counter
is checked. But it results in false positive alert on Xen/IA64
because a page 'in use' has reference count 2 on Xen/IA64.
- a page is assigned to guest domain's psudo physical address space.
  This is decremented by guest_physmap_remove_page()
- a page is allocated for a domain.
  This is decremented by the following put_page()

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>