hv: mod: do not use explicit arch name when including headers

Instead of "#include <x86/foo.h>", use "#include <asm/foo.h>".

In other words, we are adopting the same practice in Linux kernel.

Tracked-On: #5920
Signed-off-by: Liang Yi <yi.liang@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>

hypervisor/boot/multiboot/multiboot2.c

@@ -7,7 +7,7 @@
 #include <types.h>
 #include <errno.h>
 #include <multiboot.h>
-#include <x86/pgtable.h>
+#include <asm/pgtable.h>
 #include "multiboot_priv.h"
 
 /**