dccp: Remove unused declaration dccp_feat_initialise_sysctls()

This is never used, so can remove it.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230726143239.9904-1-yuehaibing@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>