clk: clk-loongson2: Switch to use devm_clk_hw_register_fixed_rate_parent_data()

Since commit 706ae644 ("clk: fixed-rate: add
devm_clk_hw_register_fixed_rate_parent_data()"), we can use the
devm_clk_hw_register_fixed_rate_parent_data() helper and from then on
there is no need to manually unregister the fixed rate hw.

Since clk_hw_unregister_fixed_rate() was not called before, we also fix
the memory leak that was present.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/8733a7485619bdb791de25201a3d7984d1849c9f.1736856470.git.zhoubinbin@loongson.cn


Signed-off-by: Stephen Boyd <sboyd@kernel.org>