video: tegra: dc: minimum window size is 1x1

Use 1x1 as the minimum window size.

Bug 1193195

Change-Id: I42e13fec82bbc2dc37bde6416088f3ae49b304b7
Signed-off-by: Jon Mayo <jmayo@nvidia.com>
Reviewed-on: http://git-master/r/173302
(cherry picked from commit 3f160560b48fdf501547b9fc1f7c5bf8bd5e32af)
Reviewed-on: http://git-master/r/190810
Reviewed-by: Eric Brower <ebrower@nvidia.com>
Tested-by: Eric Brower <ebrower@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Matthew Pedro <mapedro@nvidia.com>