boards: stm32: Enable USB domain clock when required

For boards configuring USB device, enable or configure matching domain
clock when not done already.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

boards/arm/arduino_portenta_h7/arduino_portenta_h7-common.dtsi

@@ -25,6 +25,11 @@
 	};
 };
 
+&clk_hsi48 {
+	/* HSI48 required for USB */
+	status = "okay";
+};
+
 &rcc {
 	d1cpre = <1>;
 	hpre = <1>;

boards/arm/disco_l475_iot1/disco_l475_iot1.dts

@@ -90,6 +90,12 @@
 	status = "okay";
 };
 
+&clk_msi {
+	status = "okay";
+	msi-pll-mode;
+	msi-range = <11>; /* 48MHz USB bus clk */
+};
+
 &pll {
 	div-m = <1>;
 	mul-n = <20>;