igbvf: Convert uses of __constant_<foo> to <foo>

The use of __constant_<foo> has been unnecessary for quite awhile now.

Make these uses consistent with the rest of the kernel.
Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igbvf/netdev.c

@@ -2014,12 +2014,12 @@ static inline bool igbvf_tx_csum(struct igbvf_adapter *adapter,
 
 		if (skb->ip_summed == CHECKSUM_PARTIAL) {
 			switch (skb->protocol) {
-			case __constant_htons(ETH_P_IP):
+			case htons(ETH_P_IP):
 				tu_cmd |= E1000_ADVTXD_TUCMD_IPV4;
 				if (ip_hdr(skb)->protocol == IPPROTO_TCP)
 					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
 				break;
-			case __constant_htons(ETH_P_IPV6):
+			case htons(ETH_P_IPV6):
 				if (ipv6_hdr(skb)->nexthdr == IPPROTO_TCP)
 					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
 				break;