watchdog: Remove BCM63XX_WDT

watchdog: Remove BCM63XX_WDT

Now that we can utilize the BCM7038_WDT driver, remove that one which
was not converted to the watchdog APIs. There are a couple of notable
differences with how the bcm7038_wdt driver proceeds:

- bcm63xx_wdt would register with the ad-hoc BCM63xx hardware timer API,
  but this would only be used in order to catch the interrupt *before* a
  SoC reset and make the kernel "die"

- bcm6xx_wdt would register a software timer and kick it every second in
  order to pet the watchdog, thus offering a two step watchdog process.
  This is not something that is brought over to the bcm7038_wdt as it is
  deemed unnecessary. If user-space cannot pet the watchdog, but a
  kernel timer can, the system is still in a bad shape anyway.

bcm7038_wdt is simpler in its behavior and behaves as a standard
watchdog driver and is not making use of any specific platform APIs,
therefore making it more maintainable and extensible.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211112224636.395101-8-f.fainelli@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>