iwlwifi: pcie: don't increment / decrement a bool

David reported that the code I added uses the decrement
and increment operator on a boolean variable.

Fix that.

Fixes: 0cd58ea ("iwlwifi: pcie: allow the op_mode to block the tx queues")
Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/internal.h

@@ -279,7 +279,7 @@ struct iwl_txq {
 	bool frozen;
 	u8 active;
 	bool ampdu;
-	bool block;
+	int block;
 	unsigned long wd_timeout;
 	struct sk_buff_head overflow_q;