ath10k: fill 10.4 fw wmi init cmd default values

Define 10.4 wmi init command structure and introduce new function
ath10k_wmi_10_4_op_gen_init() to fill default values for each field
which goes as part of wmi init cmd to 10.4 firmware.

Signed-off-by: Raja Mani <rmani@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>