HV: init and sanitize acrn multiboot info

Initialize and sanitize a acrn specific multiboot info struct with current
supported multiboot1 in very early boot stage, which would bring below
benifits:

- don't need to do hpa2hva convention every time when refering boot_regs;

- panic early if failed to sanitize multiboot info, so that don't need to
  check multiboot info pointer/flags and panic in later boot process;

- keep most code unchanged when introduce multiboot2 support in future;

Tracked-On: #4419

Signed-off-by: Victor Sun <victor.sun@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/Makefile

@@ -193,6 +193,7 @@ endif
 BOOT_S_SRCS += arch/x86/boot/cpu_primary.S
 BOOT_S_SRCS += arch/x86/boot/cpu_save_boot_ctx.S
 BOOT_S_SRCS += arch/x86/boot/trampoline.S
+BOOT_C_SRCS += boot/multiboot.c
 BOOT_C_SRCS += boot/reloc.c
 
 # hardware management component