[DRIVER][i.MX6][A62] Add SECO GPIO watchdog driver
This is a generic driver for GPIO-based WDTs that use two GPIOs: enable and trigger. It is based on the linux GPIO-controlled Watchdog driver.
There exists another SECO driver that can be used for similar hardware, having the compatible name "seco,apx-wdog": that one initializes the watchdog earlier in the boot process, and so is used if that more complex use case is necessary.
Edited by Gianfranco Mariotti