ACPICA: Validate GPE blocks at init time

Some of the checks done by acpi_hw_read() and acpi_hw_write(),
which are used for accessing GPE registers, are redundant in the
specific case of GPE registers and the ones that are not redundant
can be done upfront at the initialization time so as to fail the
initialization if they are not passed instead of failing every
access to the affected GPE registers going forward (including
accesses from the SCI interrupt handler).

Modify the GPE blocks initialization code accordingly.

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