NetworkPkg/TcpDxe: fix SockFreeFoo() parameter list
    
    The SockFreeFoo() callback function for NetbufFromExt() has to match the
    NET_VECTOR_EXT_FREE prototype, which takes a (VOID*) as callback argument
    (Arg). EFI_EVENT has nothing to do with NET_VECTOR_EXT_FREE. Fix the
    SockFreeFoo() parameter list.
    
    This change is a no-op in practice.
    
    Cc: Jiaxin Wu <jiaxin.wu@intel.com>
    Cc: Siyuan Fu <siyuan.fu@intel.com>
    Signed-off-by: Laszlo Ersek <lersek@redhat.com>