ACPICA: Change PlatformCommChannel ASL keyword to PCC

ACPICA commit 811e69a59cb4189ebf8b882eba74c881f598a239

The former was proposed during specification discussions but it was
dropped. This keyword was introduced to the ACPICA code base by
mistake so this commit changes the keyword representing Platform
Communication Channel to be PCC.

Link: https://github.com/acpica/acpica/commit/811e69a5


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