Use the PMUFW get_chipid call to obtain IDCODE and version register.

Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>