ACPICA: Add repair for predefined methods that return nested packages

ACPICA: Add repair for predefined methods that return nested packages

Fixes a problem where a predefined method is defined to return
a variable-length Package of sub-packages. If the length is one,
the BIOS code occasionally creates a simple single package with
no sub-packages. This code attempts to fix the problem by wrapping
a new package object around the existing package. ACPICA BZ 790.

http://acpica.org/bugzilla/show_bug.cgi?id=790

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>