For PSoC 4200 BLE device, Stop Mode wake-up is possible with P2 only. Or else, you need to use XRES.
Also please Un-Freeze the IOs initially. By default polarity of Wake-Up pin is low, so we need not explicitly mention that.
I am attaching a sample project tested in the -042 BLE Kit. it works fine when a falling edge is given to P2. Please ensure that before again putting the device to Stop mode again, the Pin is at high potential. The wake-up signal is level based.