ARM: mv78xx0: correct addr_map_cfg __initdata annotation

The annotation on the addr_map_cfg variable is in the wrong place.

Without this patch, building mv78xx0_defconfig results in:

/home/arnd/linux-arm/arch/arm/mach-mv78xx0/addr-map.c:59:2: warning: initialization from incompatible pointer type [enabled by default]
/home/arnd/linux-arm/arch/arm/mach-mv78xx0/addr-map.c:59:2: warning: (near initialization for 'addr_map_cfg.win_cfg_base') [enabled by default]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Cc: Jason Cooper <jason@lakedaemon.net>