The pcie-check.sh script was added in https://github.com/Azure/sonic-buildimage/pull/4771, but was not given executable permission. Therefore, we would see messages like:
```
Aug 26 22:54:05.536248 sonic ERR systemd[664]: pcie-check.service: Failed to execute command: Permission denied
Aug 26 22:54:05.536386 sonic ERR systemd[664]: pcie-check.service: Failed at step EXEC spawning /usr/bin/pcie-check.sh: Permission denied
Aug 26 22:54:05.536600 sonic WARNING systemd[1]: pcie-check.service: Failed with result 'exit-code'.
```
* PCIe Monitor service
* Add rescan to pcie-mon.service when it fails to get all pcie devices
* space
* Clean up
* review comments
* update the pcie status in state db
* update the failed pcie status once at the end
* Update the pcie_status in STATE_DB and rename the service
* Add log to exit the service if the configuration file doesn't exist.
* fix the build failure
* Redo the pcie rescan for pcie-check failed case.
* review comments
* review comments
* review comments