mach-ux500: make PRCMU base address dynamic

This makes the PRCMU base address be selected at runtime for U8500
and U5500 instead of being compiled-in.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/arch/arm/mach-ux500/cpu.c b/arch/arm/mach-ux500/cpu.c
index 5a43107..0190e0e 100644
--- a/arch/arm/mach-ux500/cpu.c
+++ b/arch/arm/mach-ux500/cpu.c
@@ -23,6 +23,8 @@
 
 #include "clock.h"
 
+void __iomem *_PRCMU_BASE;
+
 #ifdef CONFIG_CACHE_L2X0
 static void __iomem *l2x0_base;
 #endif