crypto: des_s390 - Checkpatch cleanup

arch/s390/crypto/crypto_des.h:18: ERROR: do not use C99 // comments

Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/arch/s390/crypto/crypto_des.h b/arch/s390/crypto/crypto_des.h
index c964b64..6210457 100644
--- a/arch/s390/crypto/crypto_des.h
+++ b/arch/s390/crypto/crypto_des.h
@@ -15,4 +15,4 @@
 
 extern int crypto_des_check_key(const u8*, unsigned int, u32*);
 
-#endif //__CRYPTO_DES_H__
+#endif /*__CRYPTO_DES_H__*/