MT#57446 invalid suffix on literal; C++11 requires a space

This commit takes care of the following:

     SBCDSMInstance.cpp:55:18: warning: invalid suffix on literal; C++11 requires a space between literal and string macro [-Wliteral-suffix]
        55 |     throw string("DSM SBC call control "DSM_SBC_CCVAR_START_DIAG" parameter not set (see call profile)'");
           |

Change-Id: I9c5ddd5b438d672e29ce0028c00df177adfbfd33

apps/sbc/call_control/dsm/SBCDSMInstance.cpp

@@ -52,7 +52,7 @@ SBCDSMInstance::SBCDSMInstance(SBCCallLeg *call, const VarMapT& values)
     appBundle = it->second;
 
   if (startDiagName.empty()) {
-    throw string("DSM SBC call control "DSM_SBC_CCVAR_START_DIAG" parameter not set (see call profile)'");
+    throw string("DSM SBC call control " DSM_SBC_CCVAR_START_DIAG " parameter not set (see call profile)'");
   }
   
   map<string,string> config_vars;