dsptools and chisel-iotesters

[codelec]

version mentioned in build.sbt for dsptools and chisel-iotesters is incorrect
https://github.com/grebe/ofdm/blob/master/build.sbt#L6
https://github.com/grebe/ofdm/blob/master/build.sbt#L7

if you are using some specific commit(not available in sonatype package) of dsptools/ chisel-iotesters then please add them as submodule