修复slvnum无法写入问题

src/main/scala/backBoard/BackBoardMst.scala

@@ -195,6 +195,10 @@ trait BackBoardMstFSMC{ this: BackBoardMstBase =>
 
     }
 
+    when( wrRegAddr === 2.U ){
+      slvNum := wrRegData
+    }
+
     when( wrRegAddr === 4.U ){
       testReg := wrRegData
     }