config: common: Add extern "C" to ble and subGHz config

In cpp projects, these headers cannot be found by the linker because of
missing `extern "C" { }` guards. This commit addresses that by adding it
to both config headers

Signed-off-by: Martin Moya <[email protected]>

Author: moyamartin

subsys/config/common/include/app_ble_config.h

@@ -18,6 +18,14 @@
 
 #include <sid_ble_link_config_ifc.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 const sid_ble_link_config_t* app_get_ble_config(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif //APP_BLE_CONFIG_H

subsys/config/common/include/app_subGHz_config.h

@@ -20,7 +20,16 @@
 #include <sid_pal_mfg_store_ifc.h>
 #include <sid_900_cfg.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 const radio_sx126x_device_config_t* get_radio_cfg(void);
 const sid_pal_mfg_store_region_t* get_mfg_cfg(void);
 struct sid_sub_ghz_links_config* app_get_sub_ghz_config(void);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif