devlink: move code to a dedicated directory

The devlink code is hard to navigate with 13kLoC in one file.
I really like the way Michal split the ethtool into per-command
files and core. It'd probably be too much to split it all up,
but we can at least separate the core parts out of the per-cmd
implementations and put it in a directory so that new commands
can be separate files.

Move the code, subsequent commit will do a partial split.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -6099,7 +6099,7 @@ S:	Supported
 F:	Documentation/networking/devlink
 F:	include/net/devlink.h
 F:	include/uapi/linux/devlink.h
-F:	net/core/devlink.c
+F:	net/devlink/
 
 DH ELECTRONICS IMX6 DHCOM/DHCOR BOARD SUPPORT
 M:	Christoph Niedermaier <cniedermaier@dh-electronics.com>

net/Makefile

@@ -23,6 +23,7 @@ obj-$(CONFIG_BPFILTER)		+= bpfilter/
 obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_KEY)		+= key/
 obj-$(CONFIG_BRIDGE)		+= bridge/
+obj-$(CONFIG_NET_DEVLINK)	+= devlink/
 obj-$(CONFIG_NET_DSA)		+= dsa/
 obj-$(CONFIG_ATALK)		+= appletalk/
 obj-$(CONFIG_X25)		+= x25/

net/core/Makefile

@@ -33,7 +33,6 @@ obj-$(CONFIG_LWTUNNEL) += lwtunnel.o
 obj-$(CONFIG_LWTUNNEL_BPF) += lwt_bpf.o
 obj-$(CONFIG_DST_CACHE) += dst_cache.o
 obj-$(CONFIG_HWBM) += hwbm.o
-obj-$(CONFIG_NET_DEVLINK) += devlink.o
 obj-$(CONFIG_GRO_CELLS) += gro_cells.o
 obj-$(CONFIG_FAILOVER) += failover.o
 obj-$(CONFIG_NET_SOCK_MSG) += skmsg.o

net/devlink/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y := leftover.o