[PATCH] ia64: fix incorrect initialization of ar.k4 for BP

The patch to move the current pointer for init_task from region 7 to
region 5 inadvertendly caused ar.k4 (CURRENT_STACK) to be initialized
improperly for the bootstrap processor.  Fix this by initializing it
to -1.
Signed-off-by: David Mosberger <davidm@hpl.hp.com>

arch/ia64/kernel/head.S

@@ -154,8 +154,7 @@ start_ap:
 #endif
 	;;
 	tpa r3=r2		// r3 == phys addr of task struct
-	;;
-	shr.u r16=r3,IA64_GRANULE_SHIFT
+	mov r16=-1
 (isBP)	br.cond.dpnt .load_current // BP stack is on region 5 --- no need to map it
 
 	// load mapping for stack (virtaddr in r2, physaddr in r3)
@@ -169,6 +168,7 @@ start_ap:
 	dep r2=-1,r3,61,3	// IMVA of task
 	;;
 	mov r17=rr[r2]
+	shr.u r16=r3,IA64_GRANULE_SHIFT
 	;;
 	dep r17=0,r17,8,24
 	;;