Initial XTLDR APIC support, finds and maps base APIC address for kernel

xtldr/modules/xtos/includes/xtos.h

@@ -29,6 +29,10 @@ XtpBootSequence(IN PEFI_FILE_HANDLE BootDir,
                 IN PXT_BOOT_PROTOCOL_PARAMETERS Parameters);
 
 
+XTCDECL
+EFI_STATUS
+XtpInitializeApicBase(IN PLIST_ENTRY MemoryMappings);
+
 XTCDECL
 EFI_STATUS
 XtpInitializeLoaderBlock(IN PLIST_ENTRY MemoryMappings,