arm, am335x: Enable Spread Spectrum for the MPU

Enable Spread Spectrum for the MPU by calculating the required
values and setting the registers accordingly.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/include/asm/arch-am33xx/clock.h b/arch/arm/include/asm/arch-am33xx/clock.h
index 7c6be4c..acf3fd5 100644
--- a/arch/arm/include/asm/arch-am33xx/clock.h
+++ b/arch/arm/include/asm/arch-am33xx/clock.h
@@ -117,4 +117,5 @@
 void do_enable_clocks(u32 *const *, u32 *const *, u8);
 void do_disable_clocks(u32 *const *, u32 *const *, u8);
 
+void set_mpu_spreadspectrum(int permille);
 #endif