i965: Use 64-bit writes for timestamp queries.

i965: Use 64-bit writes for timestamp queries.

The hardware seems to use the length of the PIPE_CONTROL command to
indicate whether the write is 64-bits or 32-bits.  Which makes sense
for immediate writes.

Daniel discovered this by writing a pattern into the query object bo
and noticing that the high 32-bits were left intact, even on those
pipe control writes that seemingly worked.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Eric Anholt <eric@anholt.net>