mfd: palmas: Stop including of_gpio.h

It does not appear that any of palmas sub-drivers are using OF-based
gpio APIs, so let's stop including this header.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220926054421.1546436-3-dmitry.torokhov@gmail.com