ACPICA: Rename nameseg length macro/define for clarity

ACPICA commit 24870bd9e73d71e2a1ff0a1e94519f8f8409e57d

ACPI_NAME_SIZE changed to ACPI_NAMESEG_SIZE
This clarifies that this is the length of an individual
nameseg, not the length of a generic namestring/namepath.
Improves understanding of the code.

Link: https://github.com/acpica/acpica/commit/24870bd9


Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>