Revert "gpiolib: annotate gpio-intialization with __must_check"

This reverts commit 0fdae42d36, which
wasn't really supposed to go in, and causes lots of annoying warnings.

Quoth Andrew:
  "Complete brainfart - I meant to drop that patch ages ago."

Quoth Greg:
  "Ick, yeah, that patch isn't ok to go in as-is, all of the callers
   need to be fixed up first, which is what I thought we had agreed on..."

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/gpio.txt

@@ -135,7 +135,7 @@ setting up a platform_device using the GPIO, is mark its direction:
 	int gpio_direction_input(unsigned gpio);
 	int gpio_direction_output(unsigned gpio, int value);
 
-The return value is zero for success, else a negative errno.  It must
+The return value is zero for success, else a negative errno.  It should
 be checked, since the get/set calls don't have error returns and since
 misconfiguration is possible.  You should normally issue these calls from
 a task context.  However, for spinlock-safe GPIOs it's OK to use them