Currently all amdgpu- options can only occur once in command line, which makes them very
inconvenient to use since users cannot override them.
This patch make them ZeroOrMore, which allows them to be overridden.
These aren't actually intended for user use
I don't think this should be done. These are for testing, and should always have a single, explicit setting. These are unstable, and users should not be trying to set or use these flags