powerpc/feature: Add CPU_FTR_NOEXECUTE to G2_LE

G2_LE has a 603 core, add CPU_FTR_NOEXECUTE.

Fixes: 385e89d5 ("powerpc/mm: add exec protection on powerpc 603")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/39a530ee41d83f49747ab3af8e39c056450b9b4d.1602489653.git.christophe.leroy@csgroup.eu