ACPI: increase ACPI_MAX_REFERENCE_COUNT for larger systems

We have some new larger ia64 systems in HP that trip over the
ACPI_MAX_REFERENCE_COUNT limit which triggers a large number of these
debug messages:

ACPI Warning (utdelete-0397): Large Reference Count (XXX) in object e0000a0ff6797ab0  [20060707]

This was increased once in the past as described in this very brief thread:

http://www.mail-archive.com/linux-acpi@vger.kernel.org/msg00890.html

Signed-off-by: Doug Chapman <doug.chapman@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>