ASH: Fix clean target.
ASH: Fix clean target.

Also include code generators in the cleaning targets.

Change-Id: Ic1eeece5152f2b13a0357363d5e902b182022fdf

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi