dt-bindings: phy: mixel,mipi-dsi-phy: Remove assigned-clock* properties

dt-bindings: phy: mixel,mipi-dsi-phy: Remove assigned-clock* properties

With dt-schema v2021.02 these properties are added by default. Some SoC
(e.g. imx8mq) configure more than just one clock using these properties.

Fixes: f9b0593dd4fc6 ("dt-bindings: phy: Convert mixel,mipi-dsi-phy to json-schema")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230609071538.149712-1-alexander.stein@ew.tq-group.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>