iwlegacy: make il3945_mac_ops __ro_after_init

There's no need for this to be only __read_mostly, since
it's only written in a single way depending on the module
parameter, so that can be moved into the module's __init
function, and the ops can be __ro_after_init.

This is a little bit safer since it means the ops can't
be overwritten (accidentally or otherwise), which would
otherwise cause an arbitrary function or bad pointer to
be called.

Signed-off-by: Johannes Berg <[e-mail]>
Acked-by: Stanislaw Gruszka <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/net/wireless/intel/iwlegacy/3945-mac.c

···
 	.attrs = il3945_sysfs_entries,
 };
 
-static struct ieee80211_ops il3945_mac_ops __read_mostly = {
+static struct ieee80211_ops il3945_mac_ops __ro_after_init = {
 	.tx = il3945_mac_tx,
 	.start = il3945_mac_start,
 	.stop = il3945_mac_stop,
···
 	SET_IEEE80211_DEV(hw, &pdev->dev);
 
 	il->cmd_queue = IL39_CMD_QUEUE_NUM;
-
-	/*
-	 * Disabling hardware scan means that mac80211 will perform scans
-	 * "the hard way", rather than using device's scan.
-	 */
-	if (il3945_mod_params.disable_hw_scan) {
-		D_INFO("Disabling hw_scan\n");
-		il3945_mac_ops.hw_scan = NULL;
-	}
 
 	D_INFO("*** LOAD DRIVER ***\n");
 	il->cfg = cfg;
···
 	int ret;
 	pr_info(DRV_DESCRIPTION ", " DRV_VERSION "\n");
 	pr_info(DRV_COPYRIGHT "\n");
+
+	/*
+	 * Disabling hardware scan means that mac80211 will perform scans
+	 * "the hard way", rather than using device's scan.
+	 */
+	if (il3945_mod_params.disable_hw_scan) {
+		pr_info("hw_scan is disabled\n");
+		il3945_mac_ops.hw_scan = NULL;
+	}
 
 	ret = il3945_rate_control_register();
 	if (ret) {