Fixed unit register blocksize brokenness.

Details:
- Fixed a breakdown in BLIS's ability to differentiate between row-stored
  and column-stored micro-panels when MR or NR is unit. When either
  register blocksize (or both) is equal to one, inspecting the strides of
  the affected packed micro-panel is no longer sufficient to determine
  whether the micro-panel is a row-stored column panel or a column-stored
  row panel (because both strides are unit). At that point, dimension
  information is necessary when invoking the bli_is_row_stored_f() and
  bli_is_col_stored_f() macros (and their "obj" counterparts). Thanks to
  Ilya Polkovnichenko for reporting this bug.
- Added panel dimensions (m and n) to obj_t, which are set in
  packm_init() and then passed into the blocked variants to support the
  aforementioned update.