fix scons

libcpu/risc-v/SConscript

@@ -17,7 +17,9 @@ elif rtconfig.CPU == "nuclei" :
 elif rtconfig.CPU == "virt64" :
     group = group
 elif rtconfig.CPU == "ch32v1" :
-    group = group    
+    group = group
+elif rtconfig.CPU == "ch32v3" :
+    group = group
 else :
     group = group + SConscript(os.path.join('common', 'SConscript'))