Free epona not properly handled with OI

[DuskTheUmbreon]

Currently, free epona hard requires ocarina and epona's song. However, the logic currently allows for using OI to play epona's song, which is obviously a problem.

Ideal fix would be to make OI and free epona compatible. That would take ASM work though.

In the meantime, I'm going to just change the logic.

Should be a quick fix, but writing logic while sick sounds like a very bad idea so I'm putting this in so I don't forget to do it later.