udev: Update initscript to check for devtmpfs

This is needed because the udev_182 now requires devtmpfs and will not work correctly
with out, so ensure that the kernel contains devtmpfs by checking /proc/filesystems.

[YOCTO #4125]

(From OE-Core rev: 4f85bb5254b3f4a9db8b419947d4bde424ce9617)

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/udev/udev/init

@@ -35,6 +35,14 @@ case "$1" in
     # propagate /dev from /sys
     echo "Starting udev"
 
+    # Check for requireed devtmpfs before trying to start udev and
+    # mount a no-existant fs.
+    if ! grep -q devtmpfs /proc/filesystems
+    then
+        echo "Missing devtmpfs, which is required for udev to run";
+        echo "Halting..."
+        halt
+    fi
     # mount the tmpfs on /dev, if not already done
     LANG=C awk '$2 == "/dev" && ($3 == "tmpfs" || $3 == "devtmpfs") { exit 1 }' /proc/mounts && {
             mount -n -o mode=0755 -t tmpfs none "/dev"