Bluetooth: Host: Remove unnecessary #ifndef

The functions `le_sc_oob_config_set`, `generate_dhkey` and
`display_passkey` in `smp.c` were only defined when
`CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY` was not defined. This created
issues at build time.

Remove the guard as the code calling those functions is not guarded
itself.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>

Author: theob-pro

subsys/bluetooth/host/smp.c

@@ -3640,7 +3640,6 @@ static uint8_t sc_smp_check_confirm(struct bt_smp *smp)
 	return 0;
 }
 
-#ifndef CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY
 static bool le_sc_oob_data_req_check(struct bt_smp *smp)
 {
 	struct bt_smp_pairing *req = (struct bt_smp_pairing *)&smp->preq[1];
@@ -3685,7 +3684,6 @@ static void le_sc_oob_config_set(struct bt_smp *smp,
 
 	info->lesc.oob_config = oob_config;
 }
-#endif /* CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY */
 
 static uint8_t smp_pairing_random(struct bt_smp *smp, struct net_buf *buf)
 {
@@ -3800,7 +3798,8 @@ static uint8_t smp_pairing_random(struct bt_smp *smp, struct net_buf *buf)
 			return BT_SMP_ERR_UNSPECIFIED;
 		}
 
-		if (smp_auth_cb && smp_auth_cb->oob_data_request) {
+		if (!IS_ENABLED(CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY) && smp_auth_cb &&
+		    smp_auth_cb->oob_data_request) {
 			struct bt_conn_oob_info info = {
 				.type = BT_CONN_OOB_LE_SC,
 				.lesc.oob_config = BT_CONN_OOB_NO_DATA,
@@ -4185,7 +4184,6 @@ static uint8_t smp_security_request(struct bt_smp *smp, struct net_buf *buf)
 }
 #endif /* CONFIG_BT_CENTRAL */
 
-#ifndef CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY
 static uint8_t generate_dhkey(struct bt_smp *smp)
 {
 	if (IS_ENABLED(CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY)) {
@@ -4227,7 +4225,6 @@ static uint8_t display_passkey(struct bt_smp *smp)
 
 	return 0;
 }
-#endif /* CONFIG_BT_SMP_OOB_LEGACY_PAIR_ONLY */
 
 #if defined(CONFIG_BT_PERIPHERAL)
 static uint8_t smp_public_key_periph(struct bt_smp *smp)