clk: ti: fix OF child-node lookup

Fix child-node lookup which by using the wrong OF helper was searching
the whole tree depth-first, something which could end up matching an
unrelated node.

Also fix the related node-reference leaks.

Fixes: 5b385a45 ("clk: ti: add support for clkctrl aliases")
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>