iommu/rockchip: Allow to compile with COMPILE_TEST

Add optional CONFIG_COMPILE_TEST to dependency list.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d0a1261..f6f259a 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -154,7 +154,8 @@
 
 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