video: tegra20: dsi: set correct fifo depth

video: tegra20: dsi: set correct fifo depth

According to Thierry Reding's commit in the linux kernel

976cebc35bed0456a42bf96073a26f251d23b264
"drm/tegra: dsi: Make FIFO depths host parameters"

correct depth of the video FIFO is 1920 *words* no *bytes*

Tested-by: Ion Agorria <ion@agorria.com> # HTC One X
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # Nvidia Tegratab T114
Signed-off-by: Jonas Schwöbel <jonasschwoebel@yahoo.de>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>