ARM: SAMSUNG: Silence empty switch warning in fimc-core.h

Add 'default' case to silence the below warning:
arch/arm/plat-samsung/include/plat/fimc-core.h:25:9:
warning: switch with no cases

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>