gpio: rename gpio-generic.c into gpio-mmio.c

This patch renames the gpio-generic.c into gpio-mmio.c.
This is because currently the file only contains code
for a memory-mapped GPIO driver. There isn't any support
for ioports or other resource type.
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Makefile

@@ -12,6 +12,9 @@ obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 # Device drivers. Generally keep list sorted alphabetically
 obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
 
+# directly supported by gpio-generic
+gpio-generic-$(CONFIG_GPIO_GENERIC)	+= gpio-mmio.o
+
 obj-$(CONFIG_GPIO_104_DIO_48E)	+= gpio-104-dio-48e.o
 obj-$(CONFIG_GPIO_104_IDIO_16)	+= gpio-104-idio-16.o
 obj-$(CONFIG_GPIO_104_IDI_48)	+= gpio-104-idi-48.o