wcn36xx: Add GTK offload to WoWLAN path

Using previously set GTK KCK and KEK material this commit adds GTK rekeying
to the WoWLAN suspend/resume path. A small error in the packing of the
up to now unused command structure is fixed as we go.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Benjamin Li <benl@squareup.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210605011140.2004643-9-bryan.odonoghue@linaro.org