arm64: dts: renesas: rcar-gen3: Remove bogus "turbo-mode" properties

On several R-Car Gen3(e) SoCs, multiple (up to 4) operating points in
the same cluster are marked with the "turbo-mode" property, which is
meant only for operating points beyond "Normal Mode".

Fix this by dropping the property from all operating points but the
"High Performance" one.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/866d06aec09e5a86dba11970f93a728b3e34e9f5.1675335086.git.geert+renesas@glider.be