intel/blorp: Rework alloc_binding_table

intel/blorp: Rework alloc_binding_table

The original blorp_alloc_binding_table helper was supposed to return the
binding table offset and map along with the surface state maps.  This isn't
quite what we want, however.  What we really want is the binding table
offsets, surface state offsets, and surface state maps.  In the GL driver,
the binding table map *is* an array of surface state offsets.  However, in
Vulkan, this isn't quite true as the entries in the binding table are
surface state offsets combined with another binding table block offset.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>