ACPICA: Interpreter: Fix Store() when implicit conversion is not possible.

For the cases such as a store of a string to an existing package
object, implement the store as a CopyObject().
This is a small departure from the ACPI specification which states
that the control method should be aborted in this case. However,
ASLTS suite depends on this behavior.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>