Pass pack schema into packm_struc_cxk*().

Details:
- Changed the interface to the packm_struc_cxk*() kernels to include
  the pack_t schema. This allows the implementation to more easily
  determine how the micro-panel is stored (row-stored column panel
  or column-stored row panel).
- Updated packm blocked variants to pass in the schema.
- Updated packm_ker_t function pointer definition accordingly.