Revert "pinctrl: bcm: ns: support updated DT binding as syscon subnode"

This reverts commit a49d784d

.

The updated binding was wrong / invalid and has been reverted. There
isn't any upstream kernel DTS using it and Broadcom isn't known to use
it neither. There is close to zero chance this will cause regression for
anyone.

Actually in-kernel bcm5301x.dtsi still uses the old good binding and so
it's broken since the driver update. This revert fixes it.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20211008205938.29925-3-zajec5@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>