[ARM] gpio_free might sleep, arm architecture

According to the documentation gpio_free should only be called from task
context only.  To make this more explicit add a might sleep to all
implementations.

This patch changes the gpio_free implementations for the arm architecture.
 DaVinci is skipped on purpose to simplify the merge process for patches
switching it over to use gpiolib as per request by David Brownell.

Signed-off-by: Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
Cc: David Brownell <david-b@pacbell.net>
Cc: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-imx/include/mach/gpio.h

@@ -1,5 +1,6 @@
 #ifndef _IMX_GPIO_H
 
+#include <linux/kernel.h>
 #include <mach/imx-regs.h>
 
 #define IMX_GPIO_ALLOC_MODE_NORMAL	0
@@ -63,6 +64,8 @@ static inline int gpio_request(unsigned gpio, const char *label)
 
 static inline void gpio_free(unsigned gpio)
 {
+	might_sleep();
+
 	imx_gpio_free(gpio);
 }