Enable vrouter build on RHEL 7.5

RHEL 7.5 has kernel version updated to 3.10.0-862.el7, which breaks
building of vrouter module.

Co-Authored-By: Raja Sivaramakrishnan <raja@juniper.net>
Co-Authored-By: Krzysztof Klimonda <krzysztof.klimonda@codilime.com>
Change-Id: Icb0467344c0023141be7e1dd9998d383bfaab14b
Closes-Bug: 1763656

linux/vhost_dev.c

@@ -461,9 +461,11 @@ vhost_setup(struct net_device *dev)
     /* follow the standard steps */
     random_ether_addr(dev->dev_addr);
     ether_setup(dev);
-
+#if (! (defined(RHEL_MAJOR) && defined(RHEL_MINOR) && \
+               (RHEL_MAJOR == 7) && (RHEL_MINOR >= 5)))
 #ifdef ETH_MAX_MTU
     dev->max_mtu = ETH_MAX_MTU;
+#endif
 #endif
     dev->needed_headroom = sizeof(struct vr_eth) + sizeof(struct agent_hdr);
     dev->netdev_ops = &vhost_dev_ops;

linux/vr_genetlink.c

@@ -20,7 +20,8 @@
 #include "vr_response.h"
 #include "vrouter.h"
 
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) || \
+    (defined(RHEL_MAJOR) && (RHEL_MAJOR >= 7) && (RHEL_MINOR >= 5))
 #define GENL_ID_GENERATE 0
 #endif /* Linux 4.10.0 */
 static int netlink_trans_request(struct sk_buff *, struct genl_info *);
@@ -218,7 +219,8 @@ vr_genetlink_init(void)
      (!(defined(RHEL_MAJOR) && (RHEL_MAJOR >= 7))))
     return genl_register_family_with_ops(&vrouter_genl_family, vrouter_genl_ops,
         ARRAY_SIZE(vrouter_genl_ops));
-#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) || \
+     (defined(RHEL_MAJOR) && (RHEL_MAJOR >= 7) && (RHEL_MINOR >= 5))
     return genl_register_family(&vrouter_genl_family);
 #else
     return genl_register_family_with_ops_groups(&vrouter_genl_family,