i40e: add DCB option to Kconfig

Allow compiling DCB related files if I40E_DCB option
is supported in the kernel configuration.

DCB is disabled by default.
Signed-off-by: Neerav Parikh <Neerav.Parikh@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Tested-By: Jack Morgan<jack.morgan@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/Kconfig

@@ -271,6 +271,14 @@ config I40E_VXLAN
 	  Say Y here if you want to use Virtual eXtensible Local Area Network
 	  (VXLAN) in the driver.
 
+config I40E_DCB
+	bool "Data Center Bridging (DCB) Support"
+	default n
+	depends on I40E && DCB
+	---help---
+	  Say Y here if you want to use Data Center Bridging (DCB) in the
+	  driver.
+
 	  If unsure, say N.
 
 config I40EVF

drivers/net/ethernet/intel/i40e/Makefile

@@ -42,3 +42,5 @@ i40e-objs := i40e_main.o \
 	i40e_txrx.o	\
 	i40e_ptp.o	\
 	i40e_virtchnl_pf.o
+
+i40e-$(CONFIG_I40E_DCB) += i40e_dcb.o i40e_dcb_nl.o