clk: ti: Simplify ti_find_clock_provider()

clk: ti: Simplify ti_find_clock_provider()

Remove using for_each_of_allnodes_from() which is not safe to use
without holding the DT spinlock. In reality that probably doesn't
matter here. This is the only user in the whole tree, so it can be
made private once removed here. The "from" argument is always NULL, so
it can be dropped as well.

There's a slight change in behavior in matching the "clock-output-names"
value as the prior code would match if the node name matched the
beginning of the value and the comparision was case insensitive. Now
it must be an exact match.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250312163330.865573-2-robh@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>