Generic sleep_micro() function

kernel/amd64/bootmain.c

@@ -7,6 +7,7 @@
 #include <mm/pmm.h>
 #include <sys/debug.h>
 #include <sys/mm.h>
+#include <sys/time.h>
 #include <uacpi/uacpi.h>
 
 #define UACPI_MEMORY_BUFFER_MAX 4096
@@ -29,7 +30,7 @@ void bootmain (void) {
 
   for (size_t i = 0; i < 1000; i++) {
     DEBUG ("i=%zu\n", i);
-    amd64_hpet_sleep_micro (1000000);
+    sleep_micro (1000000);
   }
 
   for (;;)