arm64: dts: allwinner: t527: orangepi-4a: hook up external 32k crystal

arm64: dts: allwinner: t527: orangepi-4a: hook up external 32k crystal

When the board was added, its external 32.768 KHz crystal was described
but not hooked up correctly. This meant the device had to fall back to
the SoC's internal oscillator or divide a 32 KHz clock from the main
oscillator, neither of which are accurate for the RTC. As a result the
RTC clock will drift badly.

Hook the crystal up to the RTC block and request the correct clock rate.

Fixes: de713ccb9934 ("arm64: dts: allwinner: t527: Add OrangePi 4A board")
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20250913102450.3935943-3-wens@kernel.org
Signed-off-by: Chen-Yu Tsai <wens@csie.org>