[mainline]OpenSBI-v0.9-395ff7e

lib: utils/reset: Add a sunxi watchdog reset driver

One of the watchdogs in the D1 SoC provides a "soft reset" function,
which allows software to immediately reset the entire SoC. Add a driver
so it can implement the SBI system reset function.

Signed-off-by: Samuel Holland <[email protected]>
Reviewed-by: Anup Patel <[email protected]>