Add Prime 32-bit SIMD/FP registers choices

This modifies arch_data by adding a "Prime 32-bit SIMD/FP registers" operand choice, which is referenced by C.FLW and C.FSW instructions in the c_instructions_rv32.xml file.

The addition is similar to the already existing operand of "Prime 64-bit SIMD/FP registers". It should fix the issue described in #109.

Let me know if you have any questions or suggestions,

Henry