This commit updates the watchdog timers (MWDT and RWDT)
in the following ways:
- Add seprate LL for MWDT and RWDT.
- Add a combined WDT HAL for all Watchdog Timers
- Update int_wdt.c and task_wdt.c to use WDT HAL
- Remove most dependencies on LL or direct register access
in other components. They will now use the WDT HAL
- Update use of watchdogs (including RTC WDT) in bootloader and
startup code to use the HAL layer.
Xia Xiaotian