anv: fix submission batching with perf queries
If we have 2 command buffers back to back, one with a query pool, one without, we don't want to retain the second query pool value (NULL).
Signed-off-by: Lionel Landwerlin lionel.g.landwerlin@intel.com Fixes: 0a7224f3 ("anv: group as many command buffers into a single execbuf")