Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

Check upon `num_rsp` is insufficient. A malformed event packet with a
large `num_rsp` number makes hci_extended_inquiry_result_evt() go out
of bounds. Fix it.

This patch fixes the following syzbot bug:

    https://syzkaller.appspot.com/bug?id=4bf11aa05c4ca51ce0df86e500fce486552dc8d2



Reported-by:  <syzbot+d8489a79b781849b9c46@syzkaller.appspotmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>