gpio: sa1100: include <mach/generic.h>

sa1100_init_gpio() is declared in a machine specific header so it
can be called from platform code, but the definition is in the device
driver, which causes a warning:

drivers/gpio/gpio-sa1100.c:310:13: error: no previous prototype for 'sa1100_init_gpio' [-Werror=missing-prototypes]

It's already possible to include mach/generic.h from drivers, so add
this one here as well.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-sa1100.c

···
 #include <soc/sa1100/pwer.h>
 #include <mach/hardware.h>
 #include <mach/irqs.h>
+#include <mach/generic.h>
 
 struct sa1100_gpio_chip {
 	struct gpio_chip chip;