ARM: ixp4xx: Remove feature bit accessors

We switched users of the accessors over to using syscon to inspect
the bits, or removed the need for checking them. Delete these
accessors.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220211223238.648934-11-linus.walleij@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>