modules: openthread: ble: Update after BT_LE_ADV_CONN got deprecated

This is a follow-up to commit 8cfad44.

Replace the deprecated BT_LE_ADV_CONN macro with BT_LE_ADV_CONN_FAST_2.

(cherry picked from commit f930739)

Original-Signed-off-by: Andrzej Głąbek <[email protected]>
GitOrigin-RevId: f930739
Cr-Build-Id: 8724909411128659441
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8724909411128659441
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: I5bfcc2941e33f611435850ef10cd25e964400cb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/6196367
Tested-by: ChromeOS Prod (Robot) <[email protected]>
Bot-Commit: ChromeOS Prod (Robot) <[email protected]>
Commit-Queue: ChromeOS Prod (Robot) <[email protected]>

Author: Andrzej Głąbek

modules/openthread/platform/ble.c

@@ -438,7 +438,7 @@ otError otPlatBleGapAdvStart(otInstance *aInstance, uint16_t aInterval)
 	ARG_UNUSED(aInstance);
 	ARG_UNUSED(aInterval);
 
-	int err = bt_le_adv_start(BT_LE_ADV_CONN, ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));
+	int err = bt_le_adv_start(BT_LE_ADV_CONN_FAST_2, ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));
 
 	if (err != 0 && err != -EALREADY) {
 		LOG_WRN("Advertising failed to start (err %d)", err);