leds: bcm63138: Use scopes and guards

Use scoped helpers and guards to handle DT node iterations
and spinlocks. This cuts some lines of code and eliminates
common mistakes (such as the missing of_node_put()).

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20241010-bcm63138-leds-v4-2-cdb80780a555@linaro.org


Signed-off-by: Lee Jones <lee@kernel.org>