Fix log directory path to PX4

Problem Description When running the Tools/sitl_run.sh the log symbolic link was pointing to the wrong path. This PR fixes this problem by removing the -w flag when running the px4 binary

Testing Tested by running the following command

Tools/sitl_run.sh

Additional Context

This PR fixes https://github.com/Jaeyoung-Lim/data-driven-dynamics/issues/11

ethz-asl / data-driven-dynamics

Fix log directory path to PX4 #12