arch_clear_host_user_space: set zero to args[2]

to avoid duplicated per_proc_list entry.

kernel/include/syscall.h

@@ -365,6 +365,7 @@ void reset_cputime();
 void set_cputime(int mode);
 intptr_t do_mmap(intptr_t addr0, size_t len0, int prot, int flags, int fd,
 		off_t off0);
+void clear_host_pte(uintptr_t addr, size_t len);
 typedef int32_t key_t;
 int do_shmget(key_t key, size_t size, int shmflg);
 struct process_vm;

kernel/syscall.c

@@ -833,7 +833,7 @@ SYSCALL_DECLARE(exit_group)
 	return 0;
 }
 
-static void clear_host_pte(uintptr_t addr, size_t len)
+void clear_host_pte(uintptr_t addr, size_t len)
 {
 	ihk_mc_user_context_t ctx;
 	long lerror;