boards: rp2040: set startup-delay-multiplier for applicable boards

This is based on boards in
https://github.com/raspberrypi/pico-sdk/tree/2.1.0/src/boards/include/boards
that have a custom value set for PICO_XOSC_STARTUP_DELAY_MULTIPLIER.

Signed-off-by: Xudong Zheng <[email protected]>

Author: xudongzheng

boards/adafruit/kb2040/adafruit_kb2040.dts

@@ -122,3 +122,7 @@ zephyr_udc0: &usbd {
 	regulator-always-on;
 	regulator-allowed-modes = <REGULATOR_RPI_PICO_MODE_NORMAL>;
 };
+
+&xosc {
+	startup-delay-multiplier = <64>;
+};

boards/adafruit/qt_py_rp2040/adafruit_qt_py_rp2040.dts

@@ -152,3 +152,7 @@ zephyr_udc0: &usbd {
 	regulator-always-on;
 	regulator-allowed-modes = <REGULATOR_RPI_PICO_MODE_NORMAL>;
 };
+
+&xosc {
+	startup-delay-multiplier = <64>;
+};

boards/seeed/xiao_rp2040/xiao_rp2040.dts

@@ -167,3 +167,7 @@ zephyr_udc0: &usbd {
 	regulator-always-on;
 	regulator-allowed-modes = <REGULATOR_RPI_PICO_MODE_NORMAL>;
 };
+
+&xosc {
+	startup-delay-multiplier = <64>;
+};