qos-scripts: Fix classification of ingress traffic

Set the save-mark mask for the qos_${cg} chain to 0xff instead of
0xf0.  With the old value, the nibble that was saved would be
masked during the restore, preventing ingress traffic from being
classified.  Thanks to nbd for recommending the fix.

Signed-off-by: Michael Marley <michael@michaelmarley.com>

SVN-Revision: 48388