ACPICA: EFI: Add efihello demo application

ACPICA commit 3fcc59f4755607dd066ac8ef869f0aa95e871b84

This patch adds a demo EFI application for stdin/stdout testing. This
utility can be used to narrow down root causes of porting issues.

Linux is not affected by this patch.

Link: https://github.com/acpica/acpica/commit/3fcc59f4
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>