Fixed a problem in acpi_ex_convert_to_integer
where new integers were not truncated to 32 bits for
32-bit ACPI tables. This routine converts buffers and
strings to integers.

Implemented support to store a value to an Index() on a
String object.  This is an ACPI 2.0 feature that had not
yet been implemented.

Implemented new behavior for storing objects to individual
package elements (via the Index() operator). The
previous behavior was to invoke the implicit conversion
rules if an object was already present at the index.
The new behavior is to simply delete any existing object
and directly store the new object. Although the ACPI
specification seems unclear on this subject, other ACPI
implementations behave in this manner.  (This is the root
of the AE_BAD_HEX_CONSTANT issue.)

Modified the RSDP memory scan mechanism to support the
extended checksum for ACPI 2.0 (and above) RSDPs. Note
that the search continues until a valid RSDP signature is
found with a valid checksum.
Signed-off-by: Len Brown <len.brown@intel.com>