[Bluetooth] Add constant for Bluetooth socket options level

Assign the next free socket options level to be used by the Bluetooth
protocol and address family.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/linux/socket.h b/include/linux/socket.h
index f852e1a..c22ef1c 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -291,6 +291,7 @@
 #define SOL_TIPC	271
 #define SOL_RXRPC	272
 #define SOL_PPPOL2TP	273
+#define SOL_BLUETOOTH	274
 
 /* IPX options */
 #define IPX_TYPE	1