i965: Reserve more batch space to accomodate Gen6 perfmonitors.

i965: Reserve more batch space to accomodate Gen6 perfmonitors.

Ben noticed that I said each PIPE_CONTROL was 4 DWords, but it's
actually 5 DWords on Gen6-7.  We've been reserving insufficient space
for performance monitoring on Sandybridge, which means it would likely
break if you used that functionality.  (Thankfully, no one does...)

Also, the existing number of 146 was the result of me flubbing up the
arithmetic: it should have actually been 140.

Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>