clk: tegra30: Add CSI pad clock gates

clk: tegra30: Add CSI pad clock gates

Tegra30 has CSI pad bits in both PLLD and PLLD2 clocks that are required
for the correct work of the CSI block. Add CSI pad A and pad B clock gates
with PLLD/PLLD2 parents, respectively. Add a plld2 spinlock, like one plld
uses, to prevent simultaneous access since both the PLLDx and CSIx_PAD
clocks use the same registers

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # tegra20, parallel camera
Signed-off-by: Thierry Reding <treding@nvidia.com>