CORE-V: SIMD Update - Removal of redundant SIMD mask macros in riscv-opt.h

Created by: NandniJamnadas

Removed individual mask macros and replaced them with three SIMD macros: MASK_CV_SIMD_ONE, MASK_CV_SIMD_TWO, MASK_CV_SIMD_THREE.

* `include/opcode/riscv-opc.h`: Removed redundant SIMD Mask macros and 
    replaced them with three `MASK` macros.
* `opcodes/riscv-opc.c`: Replaced corresponding mask macros to each instruction.