x86: disable zero mapping and add a boot pt for ap trampoline

the application processor trampoline needs the trampoline physical
address to be mapped for the few instructions between loading the
page table and jumping to normal memory area; setup a new pt for them.

Also make it use its stack where it needs to be directly.

With that, x86 can finally remove the 0 page from its init mapping

Change-Id: Iab3f33a2ed22570eeb47b5ab6e068c9a17c25413

arch/x86_64/kernel/include/cpulocal.h

@@ -50,6 +50,7 @@ struct x86_cpu_local_variables {
 
 struct x86_cpu_local_variables *get_x86_cpu_local_variable(int id);
 struct x86_cpu_local_variables *get_x86_this_cpu_local(void);
+void *get_x86_cpu_local_kstack(int id);
 void *get_x86_this_cpu_kstack(void);