cxgb4: Remove unused declarations

Commit e2d14b42 ("cxgb4: Remove WOL get/set ethtool support") removed
t4_wol_magic_enable() and t4_wol_pat_enable() but leave declarations.

Commit 02d805dc ("cxgb4: use new fw interface to get the VIN and smt
index") leave behind cxgb4_tp_smt_idx().

cxgb4_dcb_set_caps() is never implemented and used since introduction in
commit 76bcb31e ("cxgb4 : Add DCBx support codebase and dcbnl_ops").

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>