cleanup of code to make unloading a module "safe"
Note, that there is still cleanup issues from the memory pool...
preparing first transfer steps:
use_transfer_one is the module argument
end_of_message flag is the other part
added callback in cleanup code
moved release and added first part prior to enabling transfer
new version that now also "abuses" CS polarity to hopefully avoid CS glitches on a global basis...
Essentially we move the CS Enable/Disable fully to get managed via DMA and we ignore the HW CS
functionality