Bring the default EQ into effect space

Currently it lacks kill buttons, because it is an open debate on how this type of parameters should be implemented. Also, I fixed [Bug #1209294](https://bugs.launchpad.net/mixxx/+bug/1209294).
I did this here https://github.com/badescunicu/mixxx/commit/04b28e9d4aac4bff1e58020bea104b831d302689
So after merging that PR, I will move the code which initializes m_oldCoef above.