video: tegra: dc: remove enable/disable in set_par

Remove a work around that is no longer necessary. This fixes a strobing display
issue when scrolling or double buffering.

Bug 1161314

Change-Id: I7f74c089461b01c2f2933e14094e3190cef4726a
Signed-off-by: Jon Mayo <jmayo@nvidia.com>
Reviewed-on: http://git-master/r/162135
Reviewed-by: Automatic_Commit_Validation_User
host1x: write 32b on syncpt threshold
nvmap: improve memory mapping