u-boot on BF506F-EZKIT does not seem to work. I have tried to load elf as weel as flashed the board with u-boot.ldr.hex via VDSP - I have build my own u-boot, too - but no life on uart.
everything could be wrong, but do you have a working version?
PS! I have life in uart with EE-347 by andreas pellkofer.