Commit b6d09f78 ("pinctrl: nomadik: Drop U8540/9540 support") removes
the DB8540 pin controller driver and its config PINCTRL_DB8540.

There is some code left-over in the generic nomadik pinctrl driver, i.e.,
drivers/pinctrl/nomadik/pinctrl-nomadik.{ch}, that is still around for the
removed DB8540 pin controller driver.

Remove this remaining dead code.

This issue was discovered with ./scripts/checkkconfigsymbols.py.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20220919065435.27747-1-lukas.bulwahn@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>