iris: Don't allocate a BO per query object

iris: Don't allocate a BO per query object

Instead of allocating 4K BO per query object, we can create a large blob
of memory and split it into pieces as required.

Having one BO for multiple query objects, we don't want to wait on all
of them, instead when we write last snapshot, we create a sync point, and
check syncpoints while waiting on particular object.

Signed-off-by: Sagar Ghuge <sagar.ghuge@intel.com>