Extend I/O resource for wdt0 for at32ap7000 devices

This patch extends the I/O resource to 0xfff000cf which will enable the
watchdog driver to access the reset cause (RCAUSE) register. Making it
capable of reporting boot status.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>