devmon: re-evaluate device conditions on reconf

Device conditions tracked by devmon were lost on `initctl reload`
because the reconf path did not re-assert them.  Add devmon_reconf()
to iterate all tracked device nodes and set or clear their conditions
based on current device presence.

Signed-off-by: Mattias Walström <lazzer@gmail.com>

test/devmon.sh

@@ -42,6 +42,11 @@ test_one()
 
     mkdev "$node"
     assert_status "serv" "running"
+    assert_cond "$cond"
+
+    run "initctl reload"
+    assert_status "serv" "running"
+    assert_cond "$cond"
 
     rmdev "$node"
     assert_status "serv" "waiting"