cnic : Cleanup CONFIG_IPV6 & VLAN check

The cnic module needs to ensure that if ipv6 support is compiled as a module,
then the cnic module cannot be compiled as built-in as it depends on ipv6.
Made this check cleaner via Kconfig

Use simpler IS_ENABLED for CONFIG_VLAN_8021Q check
Signed-off-by: Anish Bhatt <anish@chelsio.com>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/Kconfig

@@ -84,7 +84,7 @@ config BNX2
 
 config CNIC
 	tristate "QLogic CNIC support"
-	depends on PCI
+	depends on PCI && (IPV6 || IPV6=n)
 	select BNX2
 	select UIO
 	---help---

drivers/net/ethernet/broadcom/cnic.c

@@ -31,7 +31,7 @@
 #include <linux/if_vlan.h>
 #include <linux/prefetch.h>
 #include <linux/random.h>
-#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
+#if IS_ENABLED(CONFIG_VLAN_8021Q)
 #define BCM_VLAN 1
 #endif
 #include <net/ip.h>
@@ -3685,7 +3685,7 @@ static int cnic_get_v4_route(struct sockaddr_in *dst_addr,
 static int cnic_get_v6_route(struct sockaddr_in6 *dst_addr,
 			     struct dst_entry **dst)
 {
-#if defined(CONFIG_IPV6) || (defined(CONFIG_IPV6_MODULE) && defined(MODULE))
+#if IS_ENABLED(CONFIG_IPV6)
 	struct flowi6 fl6;
 
 	memset(&fl6, 0, sizeof(fl6));