ext4 crypto: remove duplicate header file

Remove key.h which is included twice in crypto_fname.c
Signed-off-by: zilong.liu <liuziloong@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/crypto_fname.c

@@ -19,7 +19,6 @@
 #include <linux/gfp.h>
 #include <linux/kernel.h>
 #include <linux/key.h>
-#include <linux/key.h>
 #include <linux/list.h>
 #include <linux/mempool.h>
 #include <linux/random.h>