core: add time related macros

Fixes compilation error found at https://www.cnx-software.com/2024/12/10/arduino-core-for-zephyr-beta-released/

Co-Authored-by: Martino Facchin <m.facchin@arduino.cc>
Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>

Author: facchinm

cores/arduino/time_macros.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <zephyr/sys/time_units.h>
+
+#define clockCyclesPerMicrosecond()  (1000000 / k_cyc_to_ns_near64(1000))
+#define clockCyclesToMicroseconds(a) (a / clockCyclesPerMicrosecond())
+#define microsecondsToClockCycles(a) (a * clockCyclesPerMicrosecond())