bluetooth: uses crypto interfaces, select CRYPTO

Recent changes to hci_core.c use crypto interfaces, so select CRYPTO
to make sure that those interfaces are present.

Fixes these build errors when CRYPTO is not enabled:

net/built-in.o: In function `hci_register_dev':
(.text+0x4cf86): undefined reference to `crypto_alloc_base'
net/built-in.o: In function `hci_unregister_dev':
(.text+0x4f912): undefined reference to `crypto_destroy_tfm'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>