Removes unused argument in Helper_UpdateCR1.

Interpreter::Helper_UpdateCR1 doesn't use the argument passed to UpdateCR1. It pulls its value from the FPSCR register.
Also there was a Interpreter::Helper_UpdateCR1(float) in addition to Helper_UpdateCR1(double) that hasn't ever existed. Remove the function
declaration.
Merge pull request #314 from Sonicadvance1/Clean-UpdateCR1

Removes unused argument in Helper_UpdateCR1.