Revert "i40e: remove CONFIG_I40E_VXLAN"

This reverts commit 8fe269991aece394a7ed274f525d96c73f94109a.
The case where VXLAN is a module and i40e driver is inbuilt
will not be handled properly with this change since i40e
will have an undefined symbol vxlan_get_rx_port in it.

v2: Add a signed-off-by.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/intel/Kconfig b/drivers/net/ethernet/intel/Kconfig
index 061e4e0..4163b16 100644
--- a/drivers/net/ethernet/intel/Kconfig
+++ b/drivers/net/ethernet/intel/Kconfig
@@ -269,6 +269,17 @@
 	  To compile this driver as a module, choose M here. The module
 	  will be called i40e.
 
+config I40E_VXLAN
+	bool "Virtual eXtensible Local Area Network Support"
+	default n
+	depends on I40E && VXLAN && !(I40E=y && VXLAN=m)
+	---help---
+	  This allows one to create VXLAN virtual interfaces that provide
+	  Layer 2 Networks over Layer 3 Networks. VXLAN is often used
+	  to tunnel virtual network infrastructure in virtualized environments.
+	  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