HV: modularization cleanup instr_emul header file

separate the private macro/structure/functions, which are just used
in instr_emul.c;

and move instr_emul.h to public include path.

Tracked-On: #1842
Signed-off-by: Minggui Cao <minggui.cao@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

hypervisor/include/arch/x86/per_cpu.h

@@ -16,7 +16,7 @@
 #include <gdt.h>
 #include <timer.h>
 #include <logmsg.h>
-#include "arch/x86/guest/instr_emul.h"
+#include <instr_emul.h>
 #include <profiling.h>
 #include <security.h>