arm64: tegra: Remove undocumented Tegra194 PCIe "core_m" clock

The "core_m" clock is not documented in the Tegra194 PCIe device tree
bindings, so remove it.
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra194.dtsi

@@ -2434,9 +2434,8 @@ pcie@141a0000 {
 		pinctrl-names = "default";
 		pinctrl-0 = <&pex_rst_c5_out_state>, <&clkreq_c5_bi_dir_state>;
 
-		clocks = <&bpmp TEGRA194_CLK_PEX1_CORE_5>,
-			 <&bpmp TEGRA194_CLK_PEX1_CORE_5M>;
-		clock-names = "core", "core_m";
+		clocks = <&bpmp TEGRA194_CLK_PEX1_CORE_5>;
+		clock-names = "core";
 
 		resets = <&bpmp TEGRA194_RESET_PEX1_CORE_5_APB>,
 			 <&bpmp TEGRA194_RESET_PEX1_CORE_5>;