Bluetooth: Fix 'enable_hs' type

Fix the following build warning:

  CC [M]  net/bluetooth/hci_core.o
net/bluetooth/hci_core.c: In function ‘__check_enable_hs’:
net/bluetooth/hci_core.c:2587: warning: return from incompatible pointer type

module_param in hci_core.c passes 'enable_hs' as bool format, so fix
this variable definition type.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>