ARM: shmobile: r8a7794: Remove unnecessary #ifdef CONFIG_USE_OF

The r8a7794 support is always compiled using ARCH_MULTIPLATFORM which
selects USE_OF. So #ifdef CONFIG_USE_OF is unnecessary.

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