ARM: 8416/1: Feroceon: use of_iomap() to map register base

The chain of of_address_to_resource() and ioremap() can be replaced
with of_iomap().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>