npdm: Invert top-level conditional within ndpm_save()

Allows for denesting of the code.

npdm.c

@@ -662,19 +662,22 @@ void npdm_print(npdm_t *npdm, hactool_ctx_t *tool_ctx) {
 
 void npdm_save(npdm_t *npdm, hactool_ctx_t *tool_ctx) {
     filepath_t *json_path = &tool_ctx->settings.npdm_json_path;
-    if (json_path->valid == VALIDITY_VALID) {
-        FILE *f_json = os_fopen(json_path->os_path, OS_MODE_WRITE);
-        if (f_json == NULL) {
-            fprintf(stderr, "Failed to open %s!\n", json_path->char_path);
-            return;
-        }
-        const char *json = npdm_get_json(npdm);
-        if (fwrite(json, 1, strlen(json), f_json) != strlen(json)) {
-            fprintf(stderr, "Failed to write JSON file!\n");
-            exit(EXIT_FAILURE);
-        }
-        fclose(f_json);
+    if (json_path->valid != VALIDITY_VALID) {
+        return;
+    }
+
+    FILE *f_json = os_fopen(json_path->os_path, OS_MODE_WRITE);
+    if (f_json == NULL) {
+        fprintf(stderr, "Failed to open %s!\n", json_path->char_path);
+        return;
+    }
+
+    const char *json = npdm_get_json(npdm);
+    if (fwrite(json, 1, strlen(json), f_json) != strlen(json)) {
+        fprintf(stderr, "Failed to write JSON file!\n");
+        exit(EXIT_FAILURE);
     }
+    fclose(f_json);
 }
 
 void cJSON_AddU8ToObject(cJSON *obj, char *name, uint8_t val) {