clk: tegra: pll: Add tegra_pll_wait_for_lock to clk header

Create a wrapper interface to make use of the existing
clk_pll_wait_for_lock. This will be useful for implementations
of callbacks in Tegra SoC specific clock drivers.

Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>