Reset watchdog on FPGA reset

[Peter-van-Tol]

When starting LinuxCNC, closing the instance will trigger the watchdog. When LinuxCNC is restarted, the watchdog has_bitten pin is still HIGH. This needs then to be reset by hand. Setting it in the HAL doesn't help, because the data is first read from the FPGA, thus overwriting the setting set by setp.

Solution: the watchdog needs to be reset when the card is reset.