mcctrl pager: handle pagers more properly

the pagers are all destroyed when linux thinks there is no process left,
but there is no synchronisation with mcexec on that and some new process
might have spawned and started using these pagers in the meantime,
leading to weird crashes because an invalid pager was used.

The reason we're cleaning up pagers when no process is left is that
mcctrl does not handle pager_req_release is the linux-side process got
killed or died before the mckernel one for some reason, so:
 - move pager_req_release to a new __do_in_kernel_irq_syscall() helper
 - have free_all_process_memory_range not set MF_HOST_RELEASED on the
memobj
 - just in case, clean up everything like before on mcctrl shutdown
instead of when no process is left.

Change-Id: I53b8b9b81b1e5b807593850af17b5ea5e8471174
Refs: #1154

executer/kernel/mcctrl/driver.c

@@ -177,6 +177,7 @@ int mcctrl_os_shutdown_notifier(int os_index)
 			mdelay(200);
 		}
 
+		pager_cleanup();
 		sysfsm_cleanup(os[os_index]);
 		free_topology_info(os[os_index]);
 		ihk_os_unregister_user_call_handlers(os[os_index], mcctrl_uc + os_index);