ACPICA: Add a define for size of struct acpi_srat_generic_affinity device_handle

ACPICA commit be56820b03d8aeabfa6709c4d99bf1711afe7ef1

Replace magic number with a define. Linux kernel code will utilize this
define.

Link: https://github.com/acpica/acpica/commit/be56820b


Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>