The tgt_send_cp_big_data_stats_req() prototype was added by:
qcacld-3.0: Add support for big data stats
Change-Id I3642035d9f25237c80b529da78c51bb1ccf0035a
However a function with that name is not actually present. Instead,
the struct wlan_lmac_if_cp_stats_tx_ops::send_req_big_data_stats()
function pointer is used to send the request.
Since the prototype is unused, remove it.
Change-Id: I1a05c40d2ae639e4b6333362661e9012786a467c
CRs-Fixed: 3430267