drm: add more MMU dependencies

Many DRM drivers only work with an MMU, and after the patch to enable
core DRM support without MMU, we already had one fixup for many of them.
The etnaviv, armada and msm drivers were missed and have the same problem:

warning: (DRM_ETNAVIV) selects IOMMU_SUPPORT which has unmet direct dependencies (MMU)
warning: (DRM_I915 && DRM_MSM && DRM_ETNAVIV) selects SHMEM which has unmet direct dependencies (MMU)
drivers/gpu/drm/armada/armada_gem.o: In function `armada_gem_vm_fault':
armada_gem.c:(.text.armada_gem_vm_fault+0x14): undefined reference to `vm_insert_pfn'
arch/arm/mm/dma-mapping.c: In function '__iommu_alloc_remap':
arch/arm/mm/dma-mapping.c:1390:4: error: 'VM_ARM_DMA_CONSISTENT' undeclared (first use in this function)
arch/arm/mm/dma-mapping.c:1456:31: error: 'atomic_pool' undeclared (first use in this function); did you mean 'atomic_xor'?

Fixes: 011cda5899 ("drm: fix compilations issues introduced by "drm: allow to use mmuless SoC"")
Fixes: 62a0d98a18 ("drm: allow to use mmuless SoC")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111133357.3664191-2-arnd@arndb.de

drivers/gpu/drm/armada/Kconfig

@@ -1,6 +1,6 @@
 config DRM_ARMADA
 	tristate "DRM support for Marvell Armada SoCs"
-	depends on DRM && HAVE_CLK && ARM
+	depends on DRM && HAVE_CLK && ARM && MMU
 	select DRM_KMS_HELPER
 	help
 	  Support the "LCD" controllers found on the Marvell Armada 510