watchdog: Improve Kconfig entry ordering and dependencies

HPWDT_NMI_DECODING depends on HP_WATCHDOG and should be next to it.
This helps menuconfig identify HPWDT_NMI_DECODING as depending on
HP_WATCHDOG.

BCM_KONA_WDT_DEBUG depends on BCM_KONA_WDT which depends on COMPILE_TEST.
Enabling BCM_KONA_WDT_DEBUG without BCM_KONA_WDT does not make sense,
so drop the COMPILE_TEST dependency from it. This also improves
menuconfig, which now properly associates BCM_KONA_WDT_DEBUG with
BCM_KONA_WDT.

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