video: tegra: dc: ext: fix memleak and check args

video: tegra: dc: ext: fix memleak and check args

check overflow of win_num argument to TEGRA_DC_EXT_FLIP2 ioctl.
fix kernel memory leak when ioctl fails.
copy the correct number of window args on TEGRA_DC_EXT_FLIP ioctl.

Change-Id: I57b27f348ead1ac4cdef45a83dc2c46c9c70c582
Signed-off-by: Jon Mayo <jmayo@nvidia.com>
Reviewed-on: http://git-master/r/204183
Reviewed-by: Thomas Cherry <tcherry@nvidia.com>
Tested-by: Thomas Cherry <tcherry@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User