gpiolib/arches: Centralise bolierplate asm/gpio.h

Rather than requiring architectures that use gpiolib but don't have any
need to define anything custom to copy an asm/gpio.h provide a Kconfig
symbol which architectures must select in order to include gpio.h and
for other architectures just provide the trivial implementation directly.

This makes it much easier to do gpiolib updates and is also a step towards
making gpiolib APIs available on every architecture.

For architectures with existing boilerplate code leave a stub header in
place which warns on direct inclusion of asm/gpio.h and includes
linux/gpio.h to catch code that's doing this.  Direct inclusion of
asm/gpio.h has long been deprecated.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Jonas Bonn <jonas@southpole.se>
Acked-by: Tony Luck <tony.luck@intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/sparc/include/asm/gpio.h

@@ -1,36 +1,4 @@
-#ifndef __ASM_SPARC_GPIO_H
-#define __ASM_SPARC_GPIO_H
-
-#include <linux/errno.h>
-#include <asm-generic/gpio.h>
-
-#ifdef CONFIG_GPIOLIB
-
-static inline int gpio_get_value(unsigned int gpio)
-{
-	return __gpio_get_value(gpio);
-}
-
-static inline void gpio_set_value(unsigned int gpio, int value)
-{
-	__gpio_set_value(gpio, value);
-}
-
-static inline int gpio_cansleep(unsigned int gpio)
-{
-	return __gpio_cansleep(gpio);
-}
-
-static inline int gpio_to_irq(unsigned int gpio)
-{
-	return -ENOSYS;
-}
-
-static inline int irq_to_gpio(unsigned int irq)
-{
-	return -EINVAL;
-}
-
-#endif /* CONFIG_GPIOLIB */
-
-#endif /* __ASM_SPARC_GPIO_H */
+#ifndef __LINUX_GPIO_H
+#warning Include linux/gpio.h instead of asm/gpio.h
+#include <linux/gpio.h>
+#endif