Bluetooth: Add function and line information to bt_dbg

When enabling debug via CONFIG_BT_FEATURE_DEBUG include function and
line information by default otherwise it is hard to make any sense of
which function the logs comes from.

Signed-off-by: Luiz Augusto von Dentz <[e-mail]>

include/net/bluetooth/bluetooth.h

···
 #define BT_ERR(fmt, ...)	bt_err(fmt "\n", ##__VA_ARGS__)
 
 #if IS_ENABLED(CONFIG_BT_FEATURE_DEBUG)
-#define BT_DBG(fmt, ...)	bt_dbg(fmt "\n", ##__VA_ARGS__)
+#define BT_DBG(fmt, ...) \
+	bt_dbg("%s:%d: " fmt "\n", __func__, __LINE__, ##__VA_ARGS__)
 #else
 #define BT_DBG(fmt, ...)	pr_debug(fmt "\n", ##__VA_ARGS__)
 #endif