clk: tegra: Avoid calling an uninitialized function

clk: tegra: Avoid calling an uninitialized function

Commit 493ffb046cf5 ("clk: tegra: super: Switch to determine_rate")
replaced clk_super_round_rate() by clk_super_determine_rate(), but
didn't update one callsite that was explicitly calling the old
tegra_clk_super_ops.round_rate() function, which was now NULL. This
resulted in a crash on Tegra30 systems during early boot.

Switch this callsite over to the clk_super_determine_rate() equivalent
to avoid the crash.

Fixes: 493ffb046cf5 ("clk: tegra: super: Switch to determine_rate")
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230630130748.840729-1-thierry.reding@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>