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: David S. Miller <davem@davemloft.net>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>