drm/i915: Bump object bookkeeping to u64 from size_t

Internally we allow for using more objects than a single process can
allocate, i.e. we allow for a 64bit GPU address space even on a 32bit
system. Using size_t may oveerflow.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161018120251.25043-1-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8a1020f..cabcd06 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1389,7 +1389,7 @@
 
 	/* accounting, useful for userland debugging */
 	spinlock_t object_stat_lock;
-	size_t object_memory;
+	u64 object_memory;
 	u32 object_count;
 };