riffa.py ctype type error due to float type entered into fpga_send length argument

[dsdy120]

Raising an issue that on RIFFA v2.2.0, running on Ubuntu 20.04.6 LTS, kernel version 5.4.0-186-generic, using Python 3.8.10, using fpga_send results in an error because in line 128 of riffa.py, length variable is assigned a float value, which raises a ctype error when passed into libriffa.fpga_send. Setting length = int(datalen/4) resolves the issue, but I am unsure if this breaks anything else.