generate-tar: Call mksquashfs with -all-root option

The mksquashfs command preserves the owner of the files it squashes,
which is the login name of the user that runs generate-tar since the
partiton files are extracted into a local directory by pflash.

Bitbake sets the owner for the filesystem files to root as default,
so makes sense that the PNOR partition files are also owned by root
instead of a user name that doesn't exist on the BMC.

Tested:
Before:
root@witherspoon:~# ls -l /media/pnor-ro-652c7b59/
-rw-rw-r--    1 253760   401855       32768 Aug 15 14:39 ATTR_PERM

After:
root@witherspoon:~# ls -l /media/pnor-ro-944751fd/
-rw-rw-r--    1 root     root         32768 Sep 11 15:07 ATTR_PERM
-rw-rw-r--    1 root     root         32768 Sep 11 15:07 ATTR_TMP

Change-Id: Ic2cbed13e0da687e51a5c15041f54fef93c07be9
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/generate-tar b/generate-tar
index feebe89..85d8d7f 100755
--- a/generate-tar
+++ b/generate-tar
@@ -213,7 +213,7 @@
   echo "Creating SquashFS image..."
   # Prepare pnor file in ${pnor_dir}
   cd "${pnor_dir}"
-  mksquashfs ${tocfile} ${partitions[*]} ${scratch_dir}/pnor.xz.squashfs
+  mksquashfs ${tocfile} ${partitions[*]} ${scratch_dir}/pnor.xz.squashfs -all-root
   cd "${scratch_dir}"
   files_to_sign+=" pnor.xz.squashfs"
 else