ACPICA: Drop the repeated word "an" in a comment

ACPICA commit 9ed2c006444d1def55bc6f08164ed5d9e809c856

Link: https://github.com/acpica/acpica/commit/9ed2c006


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
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>