b43: silence a bogus gcc warning

use uninitialized_var() to avoid the following bogus warning:
  CC [M]  drivers/net/wireless/b43/debugfs.o
drivers/net/wireless/b43/debugfs.c: In function ‘b43_debugfs_read’:
drivers/net/wireless/b43/debugfs.c:355: warning: ‘ret’ may be used uninitialized in this function
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/debugfs.c

@@ -352,7 +352,7 @@ static ssize_t b43_debugfs_read(struct file *file, char __user *userbuf,
 	struct b43_wldev *dev;
 	struct b43_debugfs_fops *dfops;
 	struct b43_dfs_file *dfile;
-	ssize_t ret;
+	ssize_t uninitialized_var(ret);
 	char *buf;
 	const size_t bufsize = 1024 * 128;
 	const size_t buforder = get_order(bufsize);