video: tegra: dp: Turn off pll_dp when unused

video: tegra: dp: Turn off pll_dp when unused

Currently pll_dp is enabled in dp_setup_clk and
is never disabled. Instead, enable/disable
pll_dp along with the DP driver.

Change-Id: I51052b028482f9492a39468411c01ba2082618b0
Signed-off-by: Daniel Solomon <daniels@nvidia.com>
Reviewed-on: http://git-master/r/304570
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Jon Mayo <jmayo@nvidia.com>
Reviewed-by: Animesh Kishore <ankishore@nvidia.com>
Reviewed-by: Chao Xu <cxu@nvidia.com>