Fix for SGB controller multitap on SD2SNES mk2 (classic)

[redacted173]

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https://github.com/redacted173/sd2snes/issues/29

Not sure why, but the Xilinx compiler appears to use the last? condition as the implicit default. I was expecting it to not do anything for the 2/3 case like Altera. This bug reset controller state 2 and 3 every cycle on SD2SNES mk2 which caused those controllers not to work for Wario Blast and Bomberman GB.

It may be easiest to manually merge the change in your local changes and close this pull request.