samples: mgmt: mcumgr: smp_svr: Fix stack overflow with bt

Fixes an issue with a possible stack overflow when using the
Bluetooth transport for large mcumgr transfer, the issue was caused
by moving to a dedicated workqueue but not moving the enlarged
system workqueue overlay to the new smp workqueue.

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

samples/subsys/mgmt/mcumgr/smp_svr/overlay-bt.conf

@@ -18,7 +18,7 @@ CONFIG_MCUMGR_SMP_SHELL=y
 CONFIG_MCUMGR_SMP_REASSEMBLY_BT=y
 CONFIG_MCUMGR_BUF_SIZE=2475
 CONFIG_OS_MGMT_MCUMGR_PARAMS=y
-CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096
+CONFIG_MCUMGR_SMP_WORKQUEUE_STACK_SIZE=4608
 
 # Enable the LittleFS file system.
 CONFIG_FILE_SYSTEM=y