ARM: tegra: Skip scu_enable(scu_base) if not Cortex A9

Skip scu_enable(scu_base) if CPU is not Cortex A9 with SCU.

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Stephen Warren <swarren@nvidia.com>