Bluetooth: Fix BT_L2CAP and BT_SCO in Kconfig

If we want something "bool" built-in in something "tristate" it can't
"depend on" the tristate config option.

Report by DaveM:

   I give it 'y' just to make it happen, for both, and afterways no
   matter how many times I rerun "make oldconfig" I keep seeing things
   like this in my build:

scripts/kconfig/conf --silentoldconfig Kconfig
include/config/auto.conf:986:warning: symbol value 'm' invalid for BT_SCO
include/config/auto.conf:3156:warning: symbol value 'm' invalid for BT_L2CAP
Reported-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/bluetooth/Kconfig

@@ -31,9 +31,10 @@ menuconfig BT
 	  to Bluetooth kernel modules are provided in the BlueZ packages.  For
 	  more information, see <http://www.bluez.org/>.
 
+if BT != n
+
 config BT_L2CAP
 	bool "L2CAP protocol support"
-	depends on BT
 	select CRC16
 	help
 	  L2CAP (Logical Link Control and Adaptation Protocol) provides
@@ -42,11 +43,12 @@ config BT_L2CAP
 
 config BT_SCO
 	bool "SCO links support"
-	depends on BT
 	help
 	  SCO link provides voice transport over Bluetooth.  SCO support is
 	  required for voice applications like Headset and Audio.
 
+endif
+
 source "net/bluetooth/rfcomm/Kconfig"
 
 source "net/bluetooth/bnep/Kconfig"