intel/aubinator: Correctly read variable length structs.

intel/aubinator: Correctly read variable length structs.

Before this commit, when a group with count="0" is found, only one field
is added to the struct representing the instruction. This causes only
one entry to be printed by aubinator, for variable length groups.

With this commit we "detect" that there's a variable length group
(count="0") and store the offset of the last entry added to the struct
when reading the xml. When finally reading the aubdump file, we check
the size of the group and whether we have variable number of elements,
and in that case, reuse the last field to add the remaining elements.

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Tested-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>