ACPICA: TableManager: Export acpi_tb_scan_memory_for_rsdp()

This patch exports this function to be used by other ACPICA utilities.
Chao Guan, Bob Moore.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>