crypto: x86/poly1305 - Use TEST %reg,%reg instead of CMP $0,%reg

CMP $0,%reg can't set overflow flag, so we can use shorter TEST %reg,%reg
instruction when only zero and sign flags are checked (E,L,LE,G,GE conditions).
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/poly1305-x86_64-cryptogams.pl

@@ -251,7 +251,7 @@ $code.=<<___;
 	mov	%rax,8($ctx)
 	mov	%rax,16($ctx)
 
-	cmp	\$0,$inp
+	test	$inp,$inp
 	je	.Lno_key
 ___
 $code.=<<___ if (!$kernel);