Disconnected reset in proj/mnv2_first/ CFU

With a recent PR, we renamed the top reset port on the CFU to be "reset" instead of "rst". However, now, inside of the generated cfu.v, the top port 'reset' is not connected to anything, while a signal 'rst' appears to be undriven.

I'm not sure where 'rst' is declared; I suspect it is implicit with the nMigen generation.

This was discovered by Yosys trimming away most of the CFU.