[IA64] add one BUG_ON() to allocate_metaphysical_rr()

add one BUG_ON() to allocate_metaphysical_rr() to make sure
that rid for metaphysical address isn't collided.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r 3ad6ad720f90 xen/arch/ia64/xen/regionreg.c
--- a/xen/arch/ia64/xen/regionreg.c	Thu Aug 14 11:00:35 2008 +0900
+++ b/xen/arch/ia64/xen/regionreg.c	Wed Aug 20 15:11:39 2008 +0900
@@ -80,6 +80,7 @@
 static unsigned long allocate_metaphysical_rr(struct domain *d, int n)
 {
 	ia64_rr rrv;
+	BUG_ON(d->arch.starting_mp_rid + n >= d->arch.ending_mp_rid);
 
 	rrv.rrval = 0;	// Or else may see reserved bit fault
 	rrv.rid = d->arch.starting_mp_rid + n;