ath10k: make fw stats prints specific to firmware version

The patch makes debug stats prints fw specific by adding a new member
in wmi_ops. That way it's easier to add fw_stats support to 10.4 firmware.

Signed-off-by: Manikanta Pubbisetty <c_mpubbi@qti.qualcomm.com>
Signed-off-by: Tamizh Chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>