RDMA/hns: Fix build error again

This is not the first attempt to fix building random configurations,
unfortunately the attempt in commit a07fc0bb ("RDMA/hns: Fix build
error") caused a new problem when CONFIG_INFINIBAND_HNS_HIP06=m and
CONFIG_INFINIBAND_HNS_HIP08=y:

drivers/infiniband/hw/hns/hns_roce_main.o:(.rodata+0xe60): undefined reference to `__this_module'

Revert commits a07fc0bb ("RDMA/hns: Fix build error") and
a3e2d4c7 ("RDMA/hns: remove obsolete Kconfig comment") to get back to
the previous state, then fix the issues described there differently, by
adding more specific dependencies: INFINIBAND_HNS can now only be built-in
if at least one of HNS or HNS3 are built-in, and the individual back-ends
are only available if that code is reachable from the main driver.

Fixes: a07fc0bb ("RDMA/hns: Fix build error")
Fixes: a3e2d4c7 ("RDMA/hns: remove obsolete Kconfig comment")
Fixes: dd74282d ("RDMA/hns: Initialize the PCI device for hip08 RoCE")
Fixes: 08805fdb ("RDMA/hns: Split hw v1 driver from hns roce driver")
Link: https://lore.kernel.org/r/20191007211826.3361202-1-arnd@arndb.deSigned-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hns/Kconfig

 # SPDX-License-Identifier: GPL-2.0-only
 config INFINIBAND_HNS
-	bool "HNS RoCE Driver"
+	tristate "HNS RoCE Driver"
 	depends on NET_VENDOR_HISILICON
 	depends on ARM64 || (COMPILE_TEST && 64BIT)
+	depends on (HNS_DSAF && HNS_ENET) || HNS3
 	---help---
 	  This is a RoCE/RDMA driver for the Hisilicon RoCE engine. The engine
 	  is used in Hisilicon Hip06 and more further ICT SoC based on
 	  platform device.
 
+	  To compile HIP06 or HIP08 driver as module, choose M here.
+
 config INFINIBAND_HNS_HIP06
-	tristate "Hisilicon Hip06 Family RoCE support"
+	bool "Hisilicon Hip06 Family RoCE support"
 	depends on INFINIBAND_HNS && HNS && HNS_DSAF && HNS_ENET
+	depends on INFINIBAND_HNS=m || (HNS_DSAF=y && HNS_ENET=y)
 	---help---
 	  RoCE driver support for Hisilicon RoCE engine in Hisilicon Hip06 and
 	  Hip07 SoC. These RoCE engines are platform devices.
 
+	  To compile this driver, choose Y here: if INFINIBAND_HNS is m, this
+	  module will be called hns-roce-hw-v1
+
 config INFINIBAND_HNS_HIP08
-	tristate "Hisilicon Hip08 Family RoCE support"
+	bool "Hisilicon Hip08 Family RoCE support"
 	depends on INFINIBAND_HNS && PCI && HNS3
+	depends on INFINIBAND_HNS=m || HNS3=y
 	---help---
 	  RoCE driver support for Hisilicon RoCE engine in Hisilicon Hip08 SoC.
 	  The RoCE engine is a PCI device.
+
+	  To compile this driver, choose Y here: if INFINIBAND_HNS is m, this
+	  module will be called hns-roce-hw-v2.

drivers/infiniband/hw/hns/Makefile

@@ -9,8 +9,12 @@ hns-roce-objs := hns_roce_main.o hns_roce_cmd.o hns_roce_pd.o \
 	hns_roce_ah.o hns_roce_hem.o hns_roce_mr.o hns_roce_qp.o \
 	hns_roce_cq.o hns_roce_alloc.o hns_roce_db.o hns_roce_srq.o hns_roce_restrack.o
 
+ifdef CONFIG_INFINIBAND_HNS_HIP06
 hns-roce-hw-v1-objs := hns_roce_hw_v1.o $(hns-roce-objs)
-obj-$(CONFIG_INFINIBAND_HNS_HIP06) += hns-roce-hw-v1.o
+obj-$(CONFIG_INFINIBAND_HNS) += hns-roce-hw-v1.o
+endif
 
+ifdef CONFIG_INFINIBAND_HNS_HIP08
 hns-roce-hw-v2-objs := hns_roce_hw_v2.o hns_roce_hw_v2_dfx.o $(hns-roce-objs)
-obj-$(CONFIG_INFINIBAND_HNS_HIP08) += hns-roce-hw-v2.o
+obj-$(CONFIG_INFINIBAND_HNS) += hns-roce-hw-v2.o
+endif