Revert "dt-bindings: pinctrl: bcm4708-pinmux: rework binding to use syscon"

This reverts commit 2ae80900

.

My rework was unneeded & wrong. It replaced a clear & correct "reg"
property usage with a custom "offset" one.

Back then I didn't understand how to properly handle CRU block binding.
I heard / read about syscon and tried to use it in a totally invalid
way. That change also missed Rob's review (obviously).

Northstar's pin controller is a simple consistent hardware block that
can be cleanly mapped using a 0x24 long reg space.

Since the rework commit there wasn't any follow up modifying in-kernel
DTS files to use the new binding. Broadcom also isn't known to use that
bugged binding. There is close to zero chance this revert may actually
cause problems / regressions.

This commit is a simple revert. Example binding may (should) be updated
/ cleaned up but that can be handled separately.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211008205938.29925-1-zajec5@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>