arm, am335x: make mpu pll config configurable

upcoming support for siemens boards switches mpu pll clk in board
code. So make this configurable.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Tom Rini <trini@ti.com>
diff --git a/arch/arm/include/asm/arch-am33xx/sys_proto.h b/arch/arm/include/asm/arch-am33xx/sys_proto.h
index 6cce5a5..cbbb54e 100644
--- a/arch/arm/include/asm/arch-am33xx/sys_proto.h
+++ b/arch/arm/include/asm/arch-am33xx/sys_proto.h
@@ -32,6 +32,7 @@
 u32 get_device_type(void);
 void save_omap_boot_params(void);
 void setup_clocks_for_console(void);
+void mpu_pll_config_val(int mpull_m);
 void ddr_pll_config(unsigned int ddrpll_M);
 
 void sdelay(unsigned long);