karo: reset fdtaddr to the original value due to prevent overlap with linux kernel

karo: reset fdtaddr to the original value due to prevent overlap with linux kernel

Moving the FDT to low RAM leaves only 28KiB between the FDT start
address and the standard address to which the linux image is unpacked
during boot. Thus the linux kernel will overwrite portions of the FDT
if this is larger than 28KiB (which is already the case for TX6).

Put the FDT at the original address 16MiB from RAM start to prevent
this.