ble_mesh: Remove unused macro FRIEND_BUF_SIZE
#ifdef CONFIG_BLE_MESH_FRIEND
-#define FRIEND_BUF_SIZE (BLE_MESH_ADV_DATA_SIZE - BLE_MESH_NET_HDR_LEN)
-
/* We reserve one extra buffer for each friendship, since we need to be able
* to resend the last sent PDU, which sits separately outside of the queue.
*/
