clocksource/drivers/timer-sun4i: Advertise a real minimum delta

In the Linux kernel, the following vulnerability has been resolved: clocksource/drivers/timer-sun4i: Advertise a real minimum delta sun4i_clkevt_next_event() compensates for the timer stop/start synchronization delay by programming evt - TIMER_SYNC_TICKS into the hardware interval register. The clockevent device currently advertises TIMER_SYNC_TICKS as min_delta_ticks, so the clockevents core is allowed to call set_next_event() with evt == TIMER_SYNC_TICKS. That programs a zero-tick interval. With oneshot/highres/nohz timer operation this can leave the next event stuck, which was observed as a boot hang on Allwinner D1 after the clockevents core started reusing forced minimum-delta events. Advertise one extra tick instead, so the smallest event accepted by the core still programs at least one hardware tick after the synchronization compensation.

Where it's fixed