ARM: dts: omap36xx: Remove turbo mode for 1GHz variants

Previously, the 1GHz variants were marked as a turbo,
because that variant has reduced thermal operating range.

Now that the thermal throttling is in place, it should be
safe to remove the turbo-mode from the 1GHz variants, because
the CPU will automatically slow if the thermal limit is reached.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>