uboot-phytec

fpga: Replace char * with const char * for filename

Ensure the string for filename is always constant, otherwise it can be
corrupted by the writing.

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