Fix exit status codes

Using an exit status of -1 everywhere leads to the status being
converted to 255 when output to a calling application. While this does
signify an error it has a reserved meaning for exit status out of range.
Lets use a valid general exit status of 1 instead.

Change-Id: I326701c78985e34c430c258fe31d9e910da10405
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/control/gen-fan-zone-defs.py b/control/gen-fan-zone-defs.py
index 644ce54..e5aa39b 100755
--- a/control/gen-fan-zone-defs.py
+++ b/control/gen-fan-zone-defs.py
@@ -600,7 +600,7 @@
 
     if not args.zone_yaml or not args.fan_yaml:
         parser.print_usage()
-        sys.exit(-1)
+        sys.exit(1)
 
     with open(args.zone_yaml, 'r') as zone_input:
         zone_data = yaml.safe_load(zone_input) or {}