Bluetooth: host: fix build break if enable oob legacy pair only

enable CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY:

In function `bt_le_oob_get_local':
subsys/bluetooth/host/hci_core.c:8878:
		undefined reference to `bt_smp_le_oob_generate_sc_data'

Signed-off-by: chao an <anchao@xiaomi.com>