batman-adv: Fix signedness problem in parse_gw_bandwidth

strict_strtoul as used in parse_gw_bandwidth is defined for unsigned
long and strict_strtol should be used instead for long.
Signed-off-by: Sven Eckelmann <sven@narfation.org>

net/batman-adv/gateway_common.c

@@ -97,7 +97,7 @@ static bool parse_gw_bandwidth(struct net_device *net_dev, char *buff,
 			*tmp_ptr = '\0';
 	}
 
-	ret = strict_strtoul(buff, 10, &ldown);
+	ret = strict_strtol(buff, 10, &ldown);
 	if (ret) {
 		bat_err(net_dev,
 			"Download speed of gateway mode invalid: %s\n",
@@ -122,7 +122,7 @@ static bool parse_gw_bandwidth(struct net_device *net_dev, char *buff,
 				*tmp_ptr = '\0';
 		}
 
-		ret = strict_strtoul(slash_ptr + 1, 10, &lup);
+		ret = strict_strtol(slash_ptr + 1, 10, &lup);
 		if (ret) {
 			bat_err(net_dev,
 				"Upload speed of gateway mode invalid: "