rockchip: add support for rk3288

rockchip: add support for rk3288

The rk3288 is a 4-core Cortex-A12 SoC and shares a lot of features
with later SoCs.

Working features are general non-secure mode (the gic needs special
love for that), psci-based smp bringing cpu cores online and also
taking them offline again, psci-based suspend (the simpler variant
also included in the linux kernel, deeper suspend following later)
and I was also already able to test HYP-mode and was able to boot
a virtual kernel using kvm.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Change-Id: Ibaaa583b2e78197591a91d254339706fe732476a