ACPICA: acpidump: fix return values in ap_is_valid_checksum()

The function ap_is_valid_checksum() has a boolean name suggesting it
should return TRUE/FALSE, but incorrectly returns AE_OK on success and
has no explicit return on failure, leading to undefined behavior.

Fix by returning proper values:
 - FALSE when checksum validation fails
 - TRUE when checksum validation succeeds

Link: https://github.com/acpica/acpica/commit/479ba862


Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>