Add double-escape to a regex in settings.yaml

A backslash in regex in settings.yaml causes a failure.
Add double-escape before a backslash so it will be
treated as a character.

Change-Id: Icb11579986d261b562e965c871bf5da9ca2b8763
Signed-off-by: Sergey Solomin <sergey.solomin@us.ibm.com>
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/settings.yaml b/settings.yaml
index 7e88be0..7f02ea2 100644
--- a/settings.yaml
+++ b/settings.yaml
@@ -68,7 +68,7 @@
         type: instance_query
         keyregex: "host"
         subtree: "/org/openbmc/control"
-        matchregex: "control/(host\d*)$"
+        matchregex: "control/(host\\d*)$"
 
 # Example of using regex
 #    macaddress: