iommu: omap: add Kconfig OMAP dependency

Make CONFIG_OMAP_IOMMU depend on CONFIG_ARCH_OMAP so other
allmodconfig builds won't fail.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

drivers/iommu/Kconfig

@@ -110,6 +110,7 @@ config INTR_REMAP
 # OMAP IOMMU support
 config OMAP_IOMMU
 	bool "OMAP IOMMU Support"
+	depends on ARCH_OMAP
 	select IOMMU_API
 
 config OMAP_IOVMM