arm64: defconfig: drop GPIO_SYSFS on multiplatforms

The sysfs ABI to GPIO is marked obsolete and should not be
encouraged. Users should be encouraged to switch to using the
character device.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>