gpu: nvgpu: set aggressive_sync_destroy at runtime

gpu: nvgpu: set aggressive_sync_destroy at runtime

We currently set "aggressive_destroy" flag to destroy
sync object statically and for each sync object

Move this flag to per-platform structure so that it
can be set per-platform for all the sync objects

Also, set the default value of this flag as "false"
and set it to "true" once we have more than 64
channels in use

Bug 200141116

Change-Id: I1bc271df4f468a4087a06a27c7289ee0ec3ef29c
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/822041
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>