net: hns3: fix compile error

Currently, the rules for configuring search paths in Kbuild have
changed, this will lead some erros when compiling hns3 with the
following command:

make O=DIR M=drivers/net/ethernet/hisilicon/hns3

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.c:11:10:
fatal error: hnae3.h: No such file or directory

This patch fix it by adding $(srctree)/ prefix to the serach paths.
Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3pf/Makefile

@@ -3,7 +3,7 @@
 # Makefile for the HISILICON network device drivers.
 #
 
-ccflags-y := -Idrivers/net/ethernet/hisilicon/hns3
+ccflags-y := -I $(srctree)/drivers/net/ethernet/hisilicon/hns3
 
 obj-$(CONFIG_HNS3_HCLGE) += hclge.o
 hclge-objs = hclge_main.o hclge_cmd.o hclge_mdio.o hclge_tm.o hclge_mbx.o hclge_err.o  hclge_debugfs.o

drivers/net/ethernet/hisilicon/hns3/hns3vf/Makefile

@@ -3,7 +3,7 @@
 # Makefile for the HISILICON network device drivers.
 #
 
-ccflags-y := -Idrivers/net/ethernet/hisilicon/hns3
+ccflags-y := -I $(srctree)/drivers/net/ethernet/hisilicon/hns3
 
 obj-$(CONFIG_HNS3_HCLGEVF) += hclgevf.o
 hclgevf-objs = hclgevf_main.o hclgevf_cmd.o hclgevf_mbx.o
\ No newline at end of file