fscrypt: don't check for ENOKEY from fscrypt_get_encryption_info()

fscrypt_get_encryption_info() returns 0 if the encryption key is
unavailable; it never returns ENOKEY.  So remove checks for ENOKEY.

Link: https://lore.kernel.org/r/20191209212348.243331-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/ext4/dir.c

@@ -120,7 +120,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 
 	if (IS_ENCRYPTED(inode)) {
 		err = fscrypt_get_encryption_info(inode);
-		if (err && err != -ENOKEY)
+		if (err)
 			return err;
 	}