mips: loongson: use GPIO driver on CONFIG_GPIOLIB

The GPIO driver uses gpiolib, thus it should be compiled when
CONFIG_GPIOLIB is defined and not only CONFIG_GENERIC_GPIO.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

arch/mips/loongson/common/Makefile

@@ -4,7 +4,7 @@
 
 obj-y += setup.o init.o cmdline.o env.o time.o reset.o irq.o \
     pci.o bonito-irq.o mem.o machtype.o platform.o
-obj-$(CONFIG_GENERIC_GPIO) += gpio.o
+obj-$(CONFIG_GPIOLIB) += gpio.o
 
 #
 # Serial port support