ACPI: GTDT: Put GTDT table after parsing

The mapped GTDT table needs to be released after
the driver init.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Link: https://lore.kernel.org/r/1588910753-18543-1-git-send-email-guohanjun@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>