watchdog: Use depends instead of select for pretimeout governors

watchdog: Use depends instead of select for pretimeout governors

Watchdog pretimeout governors were enabled from the default governor
selection using "select". As a result, the default governor was always
built into the kernel, even if no watchdog driver was loaded. By using
"depends on" instead of "select", we are in better control, and the
governors can all be built as modules. At the same time, set the default
configuration option for pretimeout governors to match WATCHDOG_CORE
(meaning all pretimeout governors are by default enabled if pretimeout
support is enabled).

The practical impact of this change is minimal. Previously, selecting
a default governor automatically enabled that governor. Now, a default
governor can only be selected if that governor has been enabled.
Consequently, the order of governor selection is now reversed: The
governor selection is now first, followed by default governor selection.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>