wic: Add --no-fstab-update part option

When embedding a rootfs image (e.g. 'rootfs-dir') as a partition we
might want to keep the stock fstab for that image. In such a case, use
this option to not update the fstab and use the stock one instead.

This option allows you to specify which partitions get the fstab
updated and which get the stock fstab.

The option matches the argument you can pass to wic itself where the
same action is performed but for all the partitions.

Example:
    part /export --source rootfs --rootfs-dir=hockeycam-image
--fstype=ext4 --label export --align 1024 --no-fstab-update

    part / --source rootfs --fstype=ext4 --label rootfs --align 1024

(From OE-Core rev: ab4c95af8ecd15dc136194ab761afae756db5803)

Signed-off-by: Daniel Gomez <daniel@qtec.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/ksparser.py

@@ -185,6 +185,7 @@ class KickStart():
         part.add_argument('--use-uuid', action='store_true')
         part.add_argument('--uuid')
         part.add_argument('--fsuuid')
+        part.add_argument('--no-fstab-update', action='store_true')
 
         bootloader = subparsers.add_parser('bootloader')
         bootloader.add_argument('--append')