acpi: remove double mention of Support for ACPI option

Current description for CONFIG_ACPI includes the word "Support" twice.  One
effect of this is that in menuconfig the "--->" that indicates the presence
of sub-options will not show up unless you have a very wide console.

Signed-off-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>