Undefined width of reg_ena_i at fpnew_divsqrt_multi

https://github.com/openhwgroup/cvfpu/blob/develop/src/fpnew_divsqrt_multi.sv#L146

Hi, developers, in the case of NUM_INP_REGS is zero, reg_ena_i would be [-1:0], is that a legal condition?

Best, redpanda3