ath10k: remove obselete Copy Engine comments

Remove obselete Copy Engine comments referring to the function
ath10k_ce_sendlist_send as this function was removed long time back
by the commit 2e761b5a ("ath10k: remove ce_sendlist_send").

Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>