Bluetooth: hci_event: fix memset typo

Bluetooth: hci_event: fix memset typo

hci_le_big_sync_established_evt() currently does:

    conn->num_bis = 0;
    memset(conn->bis, 0, sizeof(conn->num_bis));

sizeof(conn->num_bis) is wrong - it would make sense to either use
conn->num_bis (before setting that to 0) or sizeof(conn->bis).
Fix it by using sizeof(conn->bis), the least intrusive change.

Luckily, nothing actually depends on this memset() working properly:
Nothing seems to ever read from conn->bis beyond conn->num_bis, and when
conn->num_bis is increased, the corresponding elements of conn->bis are
initialized. So I think this line could also just be removed.

This is a purely theoretical fix and should have no impact on actual
behavior.

Fixes: 42ecf1947135 ("Bluetooth: ISO: Do not emit LE BIG Create Sync if previous is pending")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>