clk: tegra: Fix comments for structure definitions

Some fields moved from the tegra_clk_pll struct to the tegra_pll_params
struct. Update the struct comments to reflect where the fields really
are.

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Acked-By: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>