ARM: shmobile: Rework SH73A0_SCU_BASE IOMEM() usage

Rework the IOMEM() usage for the SCU base address in the
case of sh73a0. Removes recently introduced build warnings:

arch/arm/mach-shmobile/smp-sh73a0.c:45:15: warning: initialization makes integer from pointer without a cast [enabled by default]
arch/arm/mach-shmobile/smp-sh73a0.c:45:15: warning: (near initialization for 'twd_local_timer.res[0].start') [enabled by default]
arch/arm/mach-shmobile/smp-sh73a0.c:45:15: warning: initialization makes integer from pointer without a cast [enabled by default]
/arch/arm/mach-shmobile/smp-sh73a0.c:45:15: warning: (near initialization for 'twd_local_timer.res[0].end') [enabled by default]

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>