Clean up to kernel code, Added `used' field to capabilities

With the addition of used field, capability structure can be
used for resource accounting over the capability.

src/glue/arm/memory.c

@@ -44,16 +44,6 @@ void task_init_registers(struct ktcb *task, unsigned long pc)
 	task->context.spsr = ARM_MODE_USR;
 }
 
-#if 0
-/* Sets up struct page array and the physical memory descriptor. */
-void paging_init(void)
-{
-	read_bootdesc();
-	physmem_init();
-	memory_init();
-	copy_bootdesc();
-}
-#endif
 
 /*
  * Copies global kernel entries into another pgd. Even for sub-pmd ranges