capifs: fix memory leak on remount

capifs_remount may reach 'return' statement without freeing of memory
allocated by kstrdup call

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>