Signed-off-by: maipbui <maibui@microsoft.com>
#### Why I did it
`subprocess.Popen()` and `subprocess.run()` is used with `shell=True`, which is very dangerous for shell injection.
`os` - not secure against maliciously constructed input and dangerous if used to evaluate dynamic content
#### How I did it
Replace `os` by `subprocess`
Remove unused functions
Enable pca954x idle_disconnect to avoid possible I2C device address conflict.
How I did it
Change pca954x device_attr idle_state to -2 (MUX_IDLE_DISCONNECT).
How to verify it
Cat pca954x device_attr idle_state and confirm the value is -2.
Signed-off-by: Sean Wu <sean_wu@edge-core.com>
