feat(amd64): encode the AVX-512 and BMI corpus families

Assisted-by: GLM 5.3 Flash

asm/encode.go

@@ -113,6 +113,7 @@ func (e *enc) encode(mnem string, ops []Operand) error {
 		return err
 	}
 	if isVex(base) || isEvex(base) || isKOp(base) || isGather(base) || isScatter(base) ||
+		isEvexPrefGather(base) ||
 		base == "KMOVW" || base == "KMOVQ" || base == "KMOVB" || base == "KMOVD" {
 		return e.encodeVec(base, ops, sfx)
 	}