runqemu: Specify rootfstype to qemu to avoid QA warnings

With the change to ext4 filesystems for qemu, we get boot warnings from where
it tried to mount the ext4 fileystem as ext2 and ext3 first.

Avoid these by specifying the rootfs type directly on the kernel commandline
for ext* images.

(From OE-Core rev: ad9f54a5014f2d997165d0cfd6ad7c05e62f315b)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu-internal

@@ -546,6 +546,10 @@ if [ "$MACHINE" = "qemush4" ]; then
     fi
 fi
 
+if [ "${FSTYPE:0:3}" = "ext" ]; then
+    KERNCMDLINE="$KERNCMDLINE rootfstype=$FSTYPE"
+fi
+
 if [ "$MACHINE" = "akita" ]; then
     QEMU=qemu-system-arm
     if [ "$FSTYPE" = "jffs2" ]; then