smp_svr: stack size needs to be increased from 468 (#56)

diff --git a/samples/smp_svr/mynewt/syscfg.yml b/samples/smp_svr/mynewt/syscfg.yml
index bd48253..2644ef5 100644
--- a/samples/smp_svr/mynewt/syscfg.yml
+++ b/samples/smp_svr/mynewt/syscfg.yml
@@ -36,7 +36,7 @@
     CONFIG_MGMT: 1
 
     # OS main/default task
-    OS_MAIN_STACK_SIZE: 468
+    OS_MAIN_STACK_SIZE: 1024
 
     # Lots of smaller mbufs are required for smp using typical BLE ATT MTU
     # values.