anv/query: Write both dwords in emit_zero_queries

Each query slot is a uint64_t and we were only zeroing half of it.

Fixes: 7ec6e4e6 "anv/query: implement multiview interactions"
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
(cherry picked from commit 07e214f1)