arm64: dts: freescale: imx8mp-skov: configure LDB clock automatically

arm64: dts: freescale: imx8mp-skov: configure LDB clock automatically

The comment in the DT mentions that "currently it is not possible to let
display clocks configure automatically, so we need to set them manually".

Since commit ff06ea04e4cf ("clk: imx: clk-imx8mp: Allow media_disp pixel
clock reconfigure parent rate"), this is no longer the case.

Make use of this new functionality by dropping the now unneeded
assigned-clock-rates in &media_blk_ctrl.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>