rtw89: don't flush hci queues and send h2c if power is off

When disconnecting, it warns somethings after power is off, and we can't
do HCI IO. So, add this patch to avoid below messages:

  rtw89_8852ce 0000:03:00.0: timed out to flush pci txch: 11
  rtw89_8852ce 0000:03:00.0: failed to pre-release fwcmd

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220421120903.73715-9-pkshih@realtek.com