Switch to exit_on_error mode

Switch several programs to newer exit_on_error mode.  This mode dictates
the behavior of the validation functions.

Also, valid_value recently:
- Switched the order of 2 positional arguments
- Added code to default invalid_values to ["", None] vs [""]

Changed Auto_reboot/cp_master accordingliny.

Change-Id: I3ade00d8b51d567604f59ff6c8f993f4afc864ee
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/bin/plug_ins/Auto_reboot/cp_master b/bin/plug_ins/Auto_reboot/cp_master
index e28d773..b7aad55 100755
--- a/bin/plug_ins/Auto_reboot/cp_master
+++ b/bin/plug_ins/Auto_reboot/cp_master
@@ -81,7 +81,7 @@
 
     get_plug_vars()
 
-    valid_value(AUTOBOOT_OPENBMC_HOST, ["", None])
+    valid_value(AUTOBOOT_OPENBMC_HOST)
     global AUTO_REBOOT_DISABLE
     if pgm_name == "cp_cleanup":
         AUTO_REBOOT_DISABLE = 0