Fix lint warnings.

plugins/channelrx/demoddsc/coaststations.cpp

@@ -19,7 +19,7 @@
 
 // Map from MMSI to Coast Station Name
 // From https://www.itu.int/mmsapp/coaststation/list
-QMap<QString, QString> CoastStations {
+const QMap<QString, QString> CoastStations {
     {"003311000", "AASIAAT RADIO"},
     {"004224102", "ABADAN RADIO"},
     {"004224300", "ABBAS RADIO"},

plugins/channelrx/demoddsc/coaststations.h

@@ -20,6 +20,6 @@
 
 #include <QMap>
 
-extern QMap<QString, QString> CoastStations;
+extern const QMap<QString, QString> CoastStations;
 
 #endif /* INCLUDE_COASTSTATIONS_H */