ARM: at91: always enable sam9 restart

This is need for multiple SoC in the same kernel image and DT.
As we will chose the restart function via binding.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>