Bluetooth: Host make the long workqueue stack size configurable

Add a prompt to the long workqueue stack size, so that it can be easily
fine-tuned by the application. The exact usage will depend on many factors,
such as the chosen crypto backend and target architecture, so it's not
possible to have "one size fits all" solutions based on the default values.

Signed-off-by: Johan Hedberg <johan.hedberg@silabs.com>

Author: jhedberg

subsys/bluetooth/host/Kconfig

@@ -12,13 +12,15 @@ config BT_LONG_WQ
 
 if BT_LONG_WQ
 config BT_LONG_WQ_STACK_SIZE
-	# Hidden: Long workqueue stack size. Should be derived from system
-	# requirements.
-	int
+	int "Long workqueue stack size."
 	default 4096 if NO_OPTIMIZATIONS
 	default 1400 if BT_ECC
 	default 1300 if BT_GATT_CACHING
 	default 1024
+	help
+	  The stack size used for the long workqueue. In most cases it's best to use the default
+	  values, however since the actual requirement depends on the underlying crypto backend
+	  this option can be used to finetune the stack size.
 
 config BT_LONG_WQ_PRIO
 	int "Long workqueue priority. Should be preemptible."