ath10k: Constify static qmi structs

qmi_msg_handler[] and ath10k_qmi_ops are only used as input arguments
to qmi_handle_init() which accepts const pointers to both qmi_ops and
qmi_msg_handler. Make them const to allow the compiler to put them in
read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201122234031.33432-3-rikard.falkeborn@gmail.com