clocksource/drivers/sun5i: Remove pointless struct

Remove the pointless struct added in the previous patch to make
the diff smaller.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230630201800.16501-3-mans@mansr.com