tegra: dc: Fix window id mismatch in propose ioctl

tegra: dc: Fix window id mismatch in propose ioctl

While setting window attributes for activated
windows in "tegra_dc_ext_negotiate_bw", set the
flags of unactivated windows to zero. It was
being done earlier but the indexing was wrong.
This patch fixes that.

Bug 200111607

Reviewed-on: http://git-master/r/760987
(cherry picked from commit 954490781c179dc6662062fac615d2efdb7f431b)
Change-Id: Ib8ba039659a408946f78b26c98b0aa08dcf3bbcd
Signed-off-by: Arun Swain <arswain@nvidia.com>
Reviewed-on: http://git-master/r/762435
Reviewed-by: Mitch Luban <mluban@nvidia.com>
Tested-by: Mitch Luban <mluban@nvidia.com>