Make it easier to reuse for intrinsic vrgatherei16.
VPatBinary helps encode LMUL in the instruction name,
but for vrgatherei16 it needs to encode both LMUL & EMUL in the instruction name,
like PseudoVRGATHEREI16_VV_M1_M1, and PseudoVRGATHEREI16_VV_M1_M2.
Here is my patch for vrgatherei16 based on the NFC patch https://reviews.llvm.org/D95014