Integrate gf-emc-test-suite/GRNFS-26_rs485-tx-only
Commit: seco-ne/tools/gf-emc-test-suite@6d9a31bc
rs485echo: Add TX_ONLY mode and allow to repeat forever
- '-z' for tx_only mode (yes, we are running out of useful chars...)
- '-r' for repitition now understands '0', to not stop after a counted number of cycles.
- Sort the parameters and help, some whitespace cleanups.
Fix for GRNFS-26