wifi: ath12k: fix hal_rx_buf_return_buf_manager documentation

kernel-doc flagged the following issue, so fix it:

drivers/net/wireless/ath/ath12k/hal.h:771: warning: missing initial short description on line:
 * enum hal_rx_buf_return_buf_manager

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240329-hal_rx_buf_return_buf_manager-v1-2-e62ec9dc2af9@quicinc.com