dt-bindings: clock: tegra: Add IDs for OSC clocks

Tegra has OSC, OSC_DIV2 and OSC_DIV4 clocks from OSC pads which are
the possible parents of Tegra PMC clocks clk_out_1, clk_out_2, and
clk_out_3 for Tegra30 through Tegra210.

So, this patch adds ids for these clocks.

Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>