drivers/net/wireless/wl1251: add missing kfree

In each case, the kfree already at the end of the function is also needed
in the error case.

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

// <smpl>
@exists@
local idexpression x;
statement S,S1;
expression E;
identifier fl;
expression *ptr != NULL;
@@

x = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...kfree(x)...+> }
     when any
     when != true x == NULL
x->fl
...>
(
if (x == NULL) S1
|
if (...) { ... when != x
               when forall
(
 return \(0\|<+...x...+>\|ptr\);
|
* return ...;
)
}
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/wl1251/cmd.c b/drivers/net/wireless/wl1251/cmd.c
index 81f164b..d14d69d 100644
--- a/drivers/net/wireless/wl1251/cmd.c
+++ b/drivers/net/wireless/wl1251/cmd.c
@@ -241,7 +241,7 @@
 	if (ret < 0) {
 		wl1251_error("tx %s cmd for channel %d failed",
 			     enable ? "start" : "stop", channel);
-		return ret;
+		goto out;
 	}
 
 	wl1251_debug(DEBUG_BOOT, "tx %s cmd channel %d",