clk: davinci: Use of_get_available_child_by_name()

clk: davinci: Use of_get_available_child_by_name()

Simplify of_davinci_pll_init() by using of_get_available_child_by_name().

While at it, move of_node_put(child) inside the if block to avoid
additional check if of_child is NULL.

Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20250410062040.6346-1-biju.das.jz@bp.renesas.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>