wifi: ath12k: Remove struct wmi_bcn_send_from_host_cmd

struct wmi_bcn_send_from_host_cmd is unused, so remove it.

Compile tested only.

Link: https://patch.msgid.link/20251010-ath12k-nuke-wmi_bcn_send_from_host_cmd-v1-1-6f1172b77848@oss.qualcomm.com


Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>