ACPI: APEI: Put the error injection table for error path and module exit

The mapped error injection table will be used after einj_init()
for debugfs, but it should be released for module exit and error
path of einj_init().

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>