iommu/rockchip: Allow to compile with COMPILE_TEST

Add optional CONFIG_COMPILE_TEST to dependency list.
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/Kconfig

@@ -154,7 +154,8 @@ config OMAP_IOMMU_DEBUG
 
 config ROCKCHIP_IOMMU
 	bool "Rockchip IOMMU Support"
-	depends on ARCH_ROCKCHIP
+	depends on ARM
+	depends on ARCH_ROCKCHIP || COMPILE_TEST
 	select IOMMU_API
 	select ARM_DMA_USE_IOMMU
 	help