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-db5500.c b/arch/arm/mach-ux500/cpu-db5500.c
index c9dc2ef..c01bc19 100644
--- a/arch/arm/mach-ux500/cpu-db5500.c
+++ b/arch/arm/mach-ux500/cpu-db5500.c
@@ -188,6 +188,8 @@
 	ux500_map_io();
 
 	iotable_init(u5500_io_desc, ARRAY_SIZE(u5500_io_desc));
+
+	_PRCMU_BASE = __io_address(U5500_PRCMU_BASE);
 }
 
 static int usb_db5500_rx_dma_cfg[] = {