ARM: zynq: Add support for Zynq-7000S devices

ARM: zynq: Add support for Zynq-7000S devices

Patch adds detection of Zynq-7000 base silicon configuration,
namely Dual or Single CPU. Device trees attempting to enable DUAL CORE
behavior on SINGLE CPU Zynq-7000S devices are prevented from corrupting
system behavior.

Detection of Dual or Single CPU is done via eFuses.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>