gpio: nomadik: remove dead DB8540 code from <gpio/gpio-nomadik.h>

gpio: nomadik: remove dead DB8540 code from <gpio/gpio-nomadik.h>

DB8540 support was removed in commit b6d09f780761 ("pinctrl: nomadik:
Drop U8540/9540 support"), but a couple small pieces of related code
remained in <gpio/gpio-nomadik.h>. Remove them.

Discovered while searching for CONFIG_* symbols referenced in code but
not defined in any Kconfig file.

Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260610205007.44881-1-enelsonmoore@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>