[system] Fix bad int to bool conversion for clearCredentials

[eberseth]

Problem

It was reported that WiFi.clearCredentials() was returning a bad value for success in this Community post WiFi.clearCredentials() fails? on p2 @ 5.4.1.

Rick dug into the issue and saw that there was an integer to bool conversion gone bad.

Solution

Added a comparison to zero with the int clearConfiguration() call so that int() == 0 results in a boolean true in network_clear_credentials().

Added comments for network_clear_credentials() usage.

Steps to Test

Run this while credentials are set on the device.

if(!WiFi.clearCredentials()) {
    Log.warn("clear credentials failed!");
}

References

Links to the Community, Docs, Other Issues, etc..

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[eberseth]

@technobly yea/nay?