drm/etnaviv: select CMA and DMA_CMA if available

While this is no build dependency, etnaviv will only work correctly on most
systems if CMA and DMA_CMA are enabled. Select both options if available to
avoid users ending up with a non-working GPU due to a lacking kernel config.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/Kconfig

@@ -10,6 +10,8 @@ config DRM_ETNAVIV
 	select IOMMU_API
 	select IOMMU_SUPPORT
 	select WANT_DEV_COREDUMP
+	select CMA if HAVE_DMA_CONTIGUOUS
+	select DMA_CMA if HAVE_DMA_CONTIGUOUS
 	help
 	  DRM driver for Vivante GPUs.