replace asm volatile("pause") with function

core/clock.c

@@ -4,6 +4,7 @@
 #include <zinnia/compiler.h>
 #include <zinnia/print.h>
 #include <zinnia/spin.h>
+#include <arch/cpu.h>
 #include <stdint.h>
 
 static struct clock* active_clock = nullptr;
@@ -62,6 +63,6 @@ void clock_spin_ns(uint64_t ns) {
 
     uint64_t target = clock_get_elapsed_ns() + ns;
     while (clock_get_elapsed_ns() < target) {
-        // TODO: Maybe pause?
+        arch_cpu_pause();
     }
 }