libertas: Fix lbs_prb_rsp_limit_set()

The kstrtoul() test was reversed so this always returned -ENOTSUPP.

Fixes: 27d7f477 ("net: wireless: replace strict_strtoul() with kstrtoul()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: James Cameron <quozl@laptop.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/libertas/mesh.c

@@ -233,8 +233,9 @@ static ssize_t lbs_prb_rsp_limit_set(struct device *dev,
 	memset(&mesh_access, 0, sizeof(mesh_access));
 	mesh_access.data[0] = cpu_to_le32(CMD_ACT_SET);
 
-	if (!kstrtoul(buf, 10, &retry_limit))
-		return -ENOTSUPP;
+	ret = kstrtoul(buf, 10, &retry_limit);
+	if (ret)
+		return ret;
 	if (retry_limit > 15)
 		return -ENOTSUPP;