Don't use the ITC as the faulting address for external interrupts.

We only use it for tracing and the KTR infrastructure will use ITC
for the time-stamp.

sys/ia64/ia64/exception.S

@@ -1388,7 +1388,7 @@ IVT_END(Break_Instruction)
 
 IVT_ENTRY(External_Interrupt, 0x3000)
 {	.mib
-	mov		r17=ar.itc	// Put the ITC in the trapframe.
+	mov		r17=0
 	mov		r16=ip
 	br.sptk		exception_save
 	;;

sys/ia64/ia64/interrupt.c

@@ -316,8 +316,8 @@ ia64_handle_intr(struct trapframe *tf)
 
 	critical_enter();
 	do {
-		CTR2(KTR_INTR, "INTR: ITC=%u, XIV=%u",
-		    (u_int)tf->tf_special.ifa, xiv);
+		CTR3(KTR_INTR, "INTR: XIV=%u, #%u: frame=%p", xiv,
+		    PCPU_GET(cnt.v_intr), tf);
 		if (!(ia64_handler[xiv])(td, xiv, tf)) {
 			ia64_set_eoi(0);
 			ia64_srlz_d();