DCB: fix kconfig option

Since the netlink option for DCB is necessary to actually be useful,
simplified the Kconfig option.  In addition, added useful help text for the
Kconfig option.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/Makefile b/net/Makefile
index e5af3dc..ba44604 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -56,8 +56,8 @@
 obj-$(CONFIG_IUCV)		+= iucv/
 obj-$(CONFIG_RFKILL)		+= rfkill/
 obj-$(CONFIG_NET_9P)		+= 9p/
-ifeq ($(CONFIG_DCBNL),y)
-obj-$(CONFIG_DCB)		+= dcb/
+ifneq ($(CONFIG_DCB),)
+obj-y				+= dcb/
 endif
 
 ifeq ($(CONFIG_NET),y)