Long data length change in jtag_interface.py
For the long data writes, a final string of not 128 bits will trigger a change of sca jtag fifo length.
This will in turn, trigger another change in sca jtag fifo length when the next 32 or 128 bit data string comes.
to optimize, the final, non 128 bit long string could be made into a 128 bit string with trailing zeros, saving us one driver interaction.