ARM: 6900/1: Suspend: Fix build error on ARCH_S5PC100

The current mainline codes of ARCH_S5PC100 cannot support
suspend to ram. So needs this for preventing build error.

Cc: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Kukjin Kim <kgene.kim at samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>