arm64: dts: imx8mp: Remove the reference to audio ipg clock on imx8mp

On i.MX8MP, there is no audio ipg clock, so remove the wrong reference
to this clock in dts file.
Signed-off-by: NJacky Bai <ping.bai@nxp.com>
Reviewed-by: NAbel Vesa <abel.vesa@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp.dtsi

@@ -408,7 +408,6 @@
 						  <&clk IMX8MP_CLK_GIC>,
 						  <&clk IMX8MP_CLK_AUDIO_AHB>,
 						  <&clk IMX8MP_CLK_AUDIO_AXI_SRC>,
-						  <&clk IMX8MP_CLK_IPG_AUDIO_ROOT>,
 						  <&clk IMX8MP_AUDIO_PLL1>,
 						  <&clk IMX8MP_AUDIO_PLL2>;
 				assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_800M>,
@@ -424,7 +423,6 @@
 						       <500000000>,
 						       <400000000>,
 						       <800000000>,
-						       <400000000>,
 						       <393216000>,
 						       <361267200>;
 			};