Fall back to /RADIO/models.yml in case /MODELS/models.yml is not present

and do not load models.txt unless we are explicitly converting.

radio/src/sdcard.h

@@ -62,6 +62,7 @@ const char RADIO_MODELSLIST_PATH[] = RADIO_PATH PATH_SEPARATOR "models.txt";
 const char RADIO_SETTINGS_PATH[] = RADIO_PATH PATH_SEPARATOR RADIO_FILENAME;
 #if defined(SDCARD_YAML)
 const char MODELSLIST_YAML_PATH[] = MODELS_PATH PATH_SEPARATOR "models.yml";
+const char FALLBACK_MODELSLIST_YAML_PATH[] = RADIO_PATH PATH_SEPARATOR "models.yml";
 const char RADIO_SETTINGS_YAML_PATH[] = RADIO_PATH PATH_SEPARATOR "radio.yml";
 #endif
 #define    SPLASH_FILE             "splash.png"

radio/src/storage/modelslist.cpp

@@ -352,6 +352,10 @@ bool ModelsList::loadYaml()
 {
   char line[LEN_MODELS_IDX_LINE+1];
   FRESULT result = f_open(&file, MODELSLIST_YAML_PATH, FA_OPEN_EXISTING | FA_READ);
+  if (result != FR_OK) {
+    result = f_open(&file, FALLBACK_MODELSLIST_YAML_PATH, FA_OPEN_EXISTING | FA_READ);
+  }
+
   if (result == FR_OK) {
     // YAML reader
     TRACE("YAML modelslist reader");
@@ -395,7 +399,8 @@ bool ModelsList::load(Format fmt)
   FILINFO fno;
   if (fmt == Format::txt ||
       (fmt == Format::yaml_txt &&
-       f_stat(MODELSLIST_YAML_PATH, &fno) != FR_OK)) {
+       f_stat(MODELSLIST_YAML_PATH, &fno) != FR_OK &&
+       f_stat(FALLBACK_MODELSLIST_YAML_PATH, &fno) != FR_OK)) {
     res = loadTxt();
   } else {
     res = loadYaml();

radio/src/storage/modelslist.h

@@ -108,7 +108,7 @@ public:
 #if defined(SDCARD_YAML)
     yaml,
     yaml_txt,
-    load_default = yaml_txt,
+    load_default = yaml,
 #else
     load_default = txt,
 #endif