regulator: rpi-panel-attiny: add back GPIOLIB dependency

regulator: rpi-panel-attiny: add back GPIOLIB dependency

This driver provides a gpio chip, which is only possible when GPIOLIB
is enabled, which was previously guaranteed by the CONFIG_OF_GPIO
dependency that is now gone:

ERROR: modpost: "gpiochip_get_data" [drivers/regulator/rpi-panel-attiny-regulator.ko] undefined!
ERROR: modpost: "devm_gpiochip_add_data_with_key" [drivers/regulator/rpi-panel-attiny-regulator.ko] undefined!

Add an explicit GPIOLIB dependency instead.

Fixes: bf017304fce1 ("regulator: drop unneeded dependencies on OF_GPIO")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260429135812.112514-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>