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.

Fixes: 12e1480bcb49 ("clocksource: sun4i: Report the minimum tick that we can program")
Reported-by: Indrek Kruusa <indrek.kruusa@gmail.com>
Closes: https://lore.kernel.org/linux-riscv/CA+fTLhgLmTY+exGujKf8OYYQvcEW5X5NJ_5sLq2AYL6zER2c0A@mail.gmail.com/
Assisted-by: Codex:gpt-5.5
Signed-off-by: Felix Yan <felixonmars@archlinux.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>
Tested-by: Indrek Kruusa <indrek.kruusa@gmail.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-riscv/CA+fTLhgLmTY+exGujKf8OYYQvcEW5X5NJ_5sLq2AYL6zER2c0A@mail.gmail.com/
Link: https://patch.msgid.link/20260624220434.4183732-1-felixonmars@archlinux.org

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