uboot-phytec

fpga: Add support for getting external data address and length

This function supports getting both data address and length for
existing FPGA subimage and FPGA external data.

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>