net: add Hisilicon Network Subsystem DSAF support

DSAF, namely Distributed System Area Fabric, is one of the HNS
acceleration engine implementation. This patch add DSAF driver to the
system.

hns_ae_adapt: the adaptor for registering the driver to HNAE framework
hns_dsaf_mac: MAC cover interface for GE and XGE
hns_dsaf_gmac: GE (10/100/1000G Ethernet) MAC function
hns_dsaf_xgmac: XGE (10000+G Ethernet) MAC function
hns_dsaf_main: the platform device driver for the whole hardware
hns_dsaf_misc: some misc helper function, such as LED support
hns_dsaf_ppe: packet process engine function
hns_dsaf_rcb: ring buffer function

Signed-off-by: huangdaode <huangdaode@hisilicon.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: Kenneth Lee <liguozhu@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>