SOPC component Hardware TCl file Error

Try this instead:

# callouts
set_module_property VALIDATION_CALLBACK validate
#  Module parameters
add_parameter SIMULATION INTEGER "0" ""
set_parameter_property SIMULATION DISPLAY_NAME "Enter Simulation Option"
set_parameter_property SIMULATION ALLOWED_RANGES {0:No Simulation 1:Simulation}
proc validate {} {
  set simulation 
  if {$simulation == 0} {
    send_message "Info "Disabling simulation."
  } else {
    send_message Info "Enabling simulation."
  }
}