arm: zynq: Use of_platform_populate instead of bus_probe

All new boards should be using this function instead of
of_platform_bus_probe.

Two side effects:
1. Possible to probe node which are not in the bus
2. Remove bus_id table from platform code

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