i965,anv: Set the CS stall bit on the ISP disable PIPE_CONTROL

i965,anv: Set the CS stall bit on the ISP disable PIPE_CONTROL

From the bspec docs for "Indirect State Pointers Disable":

    "At the completion of the post-sync operation associated with this
    pipe control packet, the indirect state pointers in the hardware are
    considered invalid"

So the ISP disable is a post-sync type of operation which means that it
should be combined with a CS stall.  Without this, the simulator throws
an error.

Fixes: 766d801ca "anv: emit pixel scoreboard stall before ISP disable"
Fixes: f536097f6 "i965: require pixel scoreboard stall prior to ISP disable"
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>