ARM: tegra: don't timeout if CPU is powergated

When booting secondary CPU(s) which are not yet powergated, a wrong
check lead to a timeout after 100 jiffies. With this patch, we only
delay powergating if CPUs are still not powered yet.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>