arm64: defconfig: enable devtmpfs mount option

Matching x86 and making it more convenient to run the arm64 default
kernel as distros like Ubuntu need this option.

Signed-off-by: Robert Richter <rrichter@cavium.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index c107126..1e52b74 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -56,6 +56,7 @@
 CONFIG_NET_9P_VIRTIO=y
 CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DMA_CMA=y
 CONFIG_BLK_DEV_LOOP=y
 CONFIG_VIRTIO_BLK=y