powerpc/xmon: Fix #if typo for systems without MSR[RI]

Sorry, there was a typo in the #if
signed-off-by: Jimi Xenidis <jimix@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/xmon/xmon.c

@@ -338,7 +338,7 @@ int cpus_are_in_xmon(void)
 
 static inline int unrecoverable_excp(struct pt_regs *regs)
 {
-#if defined(CONFIG_4xx) || defined(CONFIG_BOOK3E)
+#if defined(CONFIG_4xx) || defined(CONFIG_PPC_BOOK3E)
 	/* We have no MSR_RI bit on 4xx or Book3e, so we simply return false */
 	return 0;
 #else