arm64: dts: imx8mm: Drop CSI1 PHY reference clock configuration

The CSI1 PHY reference clock is limited to 125 MHz according to:
i.MX 8M Mini Applications Processor Reference Manual, Rev. 3, 11/2020
Table 5-1. Clock Root Table (continued) / page 307
Slice Index n = 123 .

Currently the IMX8MM_CLK_CSI1_PHY_REF clock is configured to be
fed directly from 1 GHz PLL2 , which overclocks them. Instead, drop
the configuration altogether, which defaults the clock to 24 MHz REF
clock input, which for the PHY reference clock is just fine.

Based on a patch from Marek Vasut for the imx8mn.

Fixes: e523b7c ("arm64: dts: imx8mm: Add CSI nodes")
Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: Fabio Estevam

arch/arm64/boot/dts/freescale/imx8mm.dtsi

@@ -1221,10 +1221,9 @@
 				compatible = "fsl,imx8mm-mipi-csi2";
 				reg = <0x32e30000 0x1000>;
 				interrupts = <GIC_SPI 17 IRQ_TYPE_LEVEL_HIGH>;
-				assigned-clocks = <&clk IMX8MM_CLK_CSI1_CORE>,
-						  <&clk IMX8MM_CLK_CSI1_PHY_REF>;
-				assigned-clock-parents = <&clk IMX8MM_SYS_PLL2_1000M>,
-							  <&clk IMX8MM_SYS_PLL2_1000M>;
+				assigned-clocks = <&clk IMX8MM_CLK_CSI1_CORE>;
+				assigned-clock-parents = <&clk IMX8MM_SYS_PLL2_1000M>;
+
 				clock-frequency = <333000000>;
 				clocks = <&clk IMX8MM_CLK_DISP_APB_ROOT>,
 					 <&clk IMX8MM_CLK_CSI1_ROOT>,