rtw88: use rtw_hci_stop() instead of rtwdev->hci.ops->stop()

Fix typo, should use rtw_hci_stop()

Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>