wifi: ath10k: Fix htt_data_tx_completion kernel-doc warning

Currently kernel-doc reports:
drivers/net/wireless/ath/ath10k/htt.h:911: warning: Cannot understand  * @brief target -> host TX completion indication message definition
 on line 911 - I thought it was a doc line

This is because even though struct htt_data_tx_completion uses the
kernel-doc marker "/**", it doesn't actual use kernel-doc syntax for
the documentation. Rather than try to update this legacy driver
documentation to use kernel-doc style, just replace the comment
marker.

No functional changes, compile tested only.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240118-ath10k-kerneldoc-v1-4-99c7e8d95aad@quicinc.com