batman-adv: use htons when possible

When comparing a network ordered value with a constant, it
is better to convert the constant at compile time by means
of htons() instead of converting the value at runtime using
ntohs().

This refactoring may slightly improve the code performance.

Moreover substitute __constant_htons() with htons() since
the latter increase readability and it is smart enough to be
as efficient as the former

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 18b1fd9..87e7e4e 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -145,7 +145,7 @@
 	struct batadv_hard_iface *primary_if = NULL;
 	struct batadv_bcast_packet *bcast_packet;
 	struct vlan_ethhdr *vhdr;
-	__be16 ethertype = __constant_htons(ETH_P_BATMAN);
+	__be16 ethertype = htons(ETH_P_BATMAN);
 	static const uint8_t stp_addr[ETH_ALEN] = {0x01, 0x80, 0xC2, 0x00,
 						   0x00, 0x00};
 	static const uint8_t ectp_addr[ETH_ALEN] = {0xCF, 0x00, 0x00, 0x00,
@@ -312,7 +312,7 @@
 	struct vlan_ethhdr *vhdr;
 	struct batadv_header *batadv_header = (struct batadv_header *)skb->data;
 	unsigned short vid __maybe_unused = BATADV_NO_FLAGS;
-	__be16 ethertype = __constant_htons(ETH_P_BATMAN);
+	__be16 ethertype = htons(ETH_P_BATMAN);
 	bool is_bcast;
 
 	is_bcast = (batadv_header->packet_type == BATADV_BCAST);