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/drivers/net/Kconfig b/drivers/net/Kconfig
index efd461d..75f9f7f 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -2451,10 +2451,10 @@
 	  driver.  DCA is a method for warming the CPU cache before data
 	  is used, with the intent of lessening the impact of cache misses.
 
-config IXGBE_DCBNL
+config IXGBE_DCB
 	bool "Data Center Bridging (DCB) Support"
 	default n
-	depends on IXGBE && DCBNL
+	depends on IXGBE && DCB
 	---help---
 	  Say Y here if you want to use Data Center Bridging (DCB) in the
 	  driver.