Bluetooth: btqca: Add a short delay before downloading the NVM

On WCN3990 downloading the NVM sometimes fails with a "TLV response
size mismatch" error:

[  174.949955] Bluetooth: btqca.c:qca_download_firmware() hci0: QCA Downloading qca/crnv21.bin
[  174.958718] Bluetooth: btqca.c:qca_tlv_send_segment() hci0: QCA TLV response size mismatch

It seems the controller needs a short time after downloading the
firmware before it is ready for the NVM. A delay as short as 1 ms
seems sufficient, make it 10 ms just in case. No event is received
during the delay, hence we don't just silently drop an extra event.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>