MIPS: RB532: Use physical addresses for gpio and device controller registers

This patch fixes the misuse of virtual addresses for the GPIO and third
device controller which would lead to problems while accessing ioremap'd
registers.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>