ACPICA: Clean up double word in comment

ACPICA commit 01f43b049722fa7613fca3c9fa657b150fae8ac1

Remove the second 'know' and 'than'.

Link: https://github.com/acpica/acpica/commit/01f43b04


Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>