i965/query: Add query->bo == NULL early return in CheckQuery hook.

i965/query: Add query->bo == NULL early return in CheckQuery hook.

If query->bo == NULL, this is a redundant CheckQuery call, and we
should simply return.  We didn't do anything anyway - we skipped the
batch flushing block, and although we called get_results(), it has an
early return and does nothing.  Why bother?

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>