fixing missing parameter name

Signed-off-by: Nick Chappell <nick@intronic.org>

Taken from: https://github.com/Icinga/puppet-icinga2/pull/22

templates/nrpe.cfg.erb

@@ -108,7 +108,7 @@ allowed_hosts=<%= scope.lookupvar('icinga2::nrpe::nrpe_allowed_hosts').join(',')
 #
 # Values: 0=do not allow arguments, 1=allow command arguments
 
-dont_blame_nrpe=<%= scope.lookupvar('icinga2::nrpe::allow_command_argument_processing') %>
+dont_blame_nrpe=<%= scope.lookupvar('icinga2::nrpe::nrpe_allow_command_argument_processing') %>