intel: Make the decoder just store addresses for bases, not buffers.

intel: Make the decoder just store addresses for bases, not buffers.

The various base addresses are simply addresses.  There may or may not
be a buffer located at those addresses.  So, it doesn't make much sense
to request one.  Just save the raw address so we can add it later, when
asking about BOs at the final <base + offset> address.

Suggested-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>