powerpc/xmon: Fix compile error with PPC_8xx=y

Rearrange the code so that mode and badaddr are only defined when
they're used.

Also unsplit the string for easier grepping, and switch from CONFIG_8xx
which is deprecated to CONFIG_PPC_8xx.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/xmon/xmon.c

@@ -1242,14 +1242,14 @@ bpt_cmds(void)
 {
 	int cmd;
 	unsigned long a;
-	int mode, i;
+	int i;
 	struct bpt *bp;
-	const char badaddr[] = "Only kernel addresses are permitted "
-		"for breakpoints\n";
 
 	cmd = inchar();
 	switch (cmd) {
-#ifndef CONFIG_8xx
+#ifndef CONFIG_PPC_8xx
+	static const char badaddr[] = "Only kernel addresses are permitted for breakpoints\n";
+	int mode;
 	case 'd':	/* bd - hardware data breakpoint */
 		mode = 7;
 		cmd = inchar();