video: tegra: host: t30: use max 2d clock

setting max 2d clock can make noticeable performance difference
in 2d limited usecase such as buffer clearing

Change-Id: I40ef999e7eeebff45b657f00293608561cae831d
Signed-off-by: Donghan Ryu <dryu@nvidia.com>
Reviewed-on: http://git-master/r/98644
Reviewed-by: Simone Willett <swillett@nvidia.com>
Tested-by: Simone Willett <swillett@nvidia.com>

Signed-off-by: skip <skip@ubuntu>