HV: Replace misused pr_fatal with pr_acrnlog

The following massages is not fatal error but should be print to serial and
sbuf at the same time. pr_fatal is not a good choice. pr_acrnlog is designed
to deal with the situation. So replace the following misused pr_fatal with
pr_acrnlog.

Signed-off-by: Kaige Fu <kaige.fu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

hypervisor/arch/x86/guest/vm.c

@@ -328,7 +328,7 @@ int prepare_vm0(void)
 	/* start vm0 BSP automatically */
 	start_vm(vm);
 
-	pr_fatal("Start VM0");
+	pr_acrnlog("Start VM0");
 
 	return 0;
 }