net: hns3: Supply missing hclge_dcb.h include file

If the header file containing a function's prototype isn't included by
the sourcefile containing the associated function, the build system
complains of missing prototypes.

Fixes the following W=1 kernel build warning(s):

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_dcb.c:453:6: warning: no previous prototype for ‘hclge_dcb_ops_set’ [-Wmissing-prototypes]

Signed-off-by: Wang Hai <wanghai38@huawei.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>