Revert "mvebu: 5.10 fix DVFS caused random boot crashes"

Based on the discussion on the mailing list [1], the patch which was
reverted, it reverts only one patch without the subsequent ones.

This leads to the SoC scaling issue not using a CPU parent clock, but
it uses DDR clock. This is done for all variants, and it's wrong because
commits (hacks) that were using the DDR clock are no longer in the mainline kernel.

If someone has stability issues on 1.2 GHz, it should not affect all
routers (1 GHz, 800 MHz) and it should be rather consulted with guys, who are trying to
improve the situation in the kernel and not making the situation worse.

There are two solutions in cases of instability:
a) disable cpufreq
b) underclock it up to 1 GHz

This reverts commit 080a0b7.

[1] https://lists.openwrt.org/pipermail/openwrt-devel/2021-June/035702.html

Fixes: d379476 ("mvebu: armada-37xx: add patch to forbid cpufreq for 1.2 GHz")
CC: Pali Rohár <pali@kernel.org>
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>