i965: update Makefile.sources for perf changes

brw_performance_query_metrics.h was removed in
134e750e and
brw_performance_query.h was removed in
8ae66679

remove reference to these files from Makefile.sources

Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
Fixes: 134e750e ("i965: extract performance query metrics")
Fixes: 8ae66679 ("intel/perf: move query_object into perf")
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
(cherry picked from commit 34dda0ca)