debugger: Fix setenv command to allow spaces.

To allow setting boot-command to "0 bootr -v debug=0x144" for example.

debugger/debugger.cpp

@@ -674,7 +674,8 @@ void enter_debugger() {
         } else if (cmd == "setenv") {
             string var_name, value;
             ss >> var_name;
-            ss >> value;
+            std::istream::sentry se(ss); // skip white space
+            getline(ss, value); // get everything up to eol
             if (ofnvram->init())
                 continue;
             ofnvram->setenv(var_name, value);