[POWERPC] Fix mpc52xx serial driver to work for arch/ppc again

The mpc52xx_uart_of_enumerate() function was added when adding 52xx
support to arch/powerpc, but it must not be called for arch/ppc.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/drivers/serial/mpc52xx_uart.c b/drivers/serial/mpc52xx_uart.c
index 9d11a75..3c4b6c2 100644
--- a/drivers/serial/mpc52xx_uart.c
+++ b/drivers/serial/mpc52xx_uart.c
@@ -789,7 +789,9 @@
 static int __init
 mpc52xx_console_init(void)
 {
+#if defined(CONFIG_PPC_MERGE)
 	mpc52xx_uart_of_enumerate();
+#endif
 	register_console(&mpc52xx_console);
 	return 0;
 }