crypto: vmac - Make VMAC work when blocks aren't aligned

VMAC implementation, as it is, does not work with blocks that
are not multiples of 128-bytes.  Furthermore, this is a problem
when using the implementation on scatterlists, even
when the complete plain text is 128-byte multiple, as the pieces
that get passed to vmac_update can be pretty much any size.

I also added test cases for unaligned blocks.

Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/vmac.h

@@ -56,6 +56,8 @@ typedef u64 vmac_t;
 struct vmac_ctx_t {
 	struct crypto_cipher *child;
 	struct vmac_ctx __vmac_ctx;
+	u8 partial[VMAC_NHBYTES];	/* partial block */
+	int partial_size;		/* size of the partial block */
 };
 
 #endif /* __CRYPTO_VMAC_H */