net: dcb: use obj-$(CONFIG_DCB) form in net/Makefile

CONFIG_DCB is a bool option. Change the ifeq conditional to the
standard obj-$(CONFIG_DCB) form.

Use obj-y in net/dcb/Makefile because Kbuild visits this Makefile
only when CONFIG_DCB=y.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20210125231659.106201-2-masahiroy@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/Makefile

@@ -55,9 +55,7 @@ obj-$(CONFIG_SMC)		+= smc/
 obj-$(CONFIG_RFKILL)		+= rfkill/
 obj-$(CONFIG_NET_9P)		+= 9p/
 obj-$(CONFIG_CAIF)		+= caif/
-ifneq ($(CONFIG_DCB),)
-obj-y				+= dcb/
-endif
+obj-$(CONFIG_DCB)		+= dcb/
 obj-$(CONFIG_6LOWPAN)		+= 6lowpan/
 obj-$(CONFIG_IEEE802154)	+= ieee802154/
 obj-$(CONFIG_MAC802154)		+= mac802154/

net/dcb/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_DCB) += dcbnl.o dcbevent.o
+obj-y += dcbnl.o dcbevent.o