net/rfkill/rfkill-gpio.c: introduce missing kfree

Error handling code following a kmalloc should free the allocated data.
The label fail_alloc already does this for rfkill.

A simplified version of the semantic match that finds the problem is as
follows: (http://coccinelle.lip6.fr)

// <smpl>
@r exists@
local idexpression x;
statement S;
identifier f1;
position p1,p2;
expression *ptr != NULL;
@@

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
x->f1
...>
(
 return \(0\|<+...x...+>\|ptr\);
|
 return@p2 ...;
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/rfkill/rfkill-gpio.c

@@ -105,7 +105,7 @@ static int rfkill_gpio_probe(struct platform_device *pdev)
 		ret = pdata->gpio_runtime_setup(pdev);
 		if (ret) {
 			pr_warn("%s: can't set up gpio\n", __func__);
-			return ret;
+			goto fail_alloc;
 		}
 	}