ath10k: add qmi service helpers for wcn3990 qmi client

WLAN qmi server running in Q6 exposes host to target
cold boot qmi handshakes. Add WLAN QMI service helpers
for ath10k wcn3990 qmi client.

Signed-off-by: Govind Singh <govinds@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Niklas Cassel <niklas.cassel@linaro.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>