iwlwifi: fix locking assertions

spin_is_locked() can return zero on some (UP?)
configurations because locks don't exist, and
that causes an endless amount of warnings. Use
lockdep_assert_held() instead, which has two
advantages:
 1) it verifies the current task is holding
    the lock or mutex
 2) it compiles away completely when lockdep
    is not enabled

Cc: stable@kernel.org [2.6.34+, maybe only parts of patch]
Reported-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-sta.c b/drivers/net/wireless/iwlwifi/iwl-sta.c
index 9511f03..7e0829b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-sta.c
+++ b/drivers/net/wireless/iwlwifi/iwl-sta.c
@@ -773,7 +773,7 @@
 
 int iwl_restore_default_wep_keys(struct iwl_priv *priv)
 {
-	WARN_ON(!mutex_is_locked(&priv->mutex));
+	lockdep_assert_held(&priv->mutex);
 
 	return iwl_send_static_wepkey_cmd(priv, 0);
 }
@@ -784,7 +784,7 @@
 {
 	int ret;
 
-	WARN_ON(!mutex_is_locked(&priv->mutex));
+	lockdep_assert_held(&priv->mutex);
 
 	IWL_DEBUG_WEP(priv, "Removing default WEP key: idx=%d\n",
 		      keyconf->keyidx);
@@ -808,7 +808,7 @@
 {
 	int ret;
 
-	WARN_ON(!mutex_is_locked(&priv->mutex));
+	lockdep_assert_held(&priv->mutex);
 
 	if (keyconf->keylen != WEP_KEY_LEN_128 &&
 	    keyconf->keylen != WEP_KEY_LEN_64) {