ARM: dts: sun8i: Enable ARM architected timer on A23

The A23 SoC has the architected timer, but the existing firmware from
Allwinner does not set CNTFRQ at all.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>