[IA64] gpio: GENERIC_GPIO default must be n

Since GPIOLIB is optional on ia64, GENERIC_GPIO must not be selected by
default.  If GPIOLIB is enabled, it will select GENERIC_GPIO.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Tony Luck <tony.luck@intel.com>