This reverts commit ed9500c1.

The clock-frequency property was meant to aid platforms with broken firmwares
that don't set up the timer properly on their own. Don't include it where it is
not the case.
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211202004328.459899-1-konrad.dybcio@somainline.org