On module unload wait for relese callback for each packag_die entry
and then free the memory. This is done by waiting on a completion
object, till release() callback.

While here, also change to kobject_init_and_add() to
kobject_create_and_add() to simplify.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>