powerpc/5xxx: Add common mpc5xxx_get_bus_frequency() function

So far, MPC512x used mpc512x_find_ips_freq() to get the bus frequency,
while MPC52xx used mpc52xx_find_ipb_freq().  Despite the different
clock names (IPS vs. IPB) the code was identical.

Use common code for both processor families.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/powerpc/include/asm/mpc5xxx.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
+ *
+ * Author: John Rigby, <jrigby@freescale.com>, Friday Apr 13 2007
+ *
+ * Description:
+ * MPC5xxx Prototypes and definitions
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#ifndef __ASM_POWERPC_MPC5xxx_H__
+#define __ASM_POWERPC_MPC5xxx_H__
+
+extern unsigned long mpc5xxx_get_bus_frequency(struct device_node *node);
+
+#endif /* __ASM_POWERPC_MPC5xxx_H__ */
+