[CRYPTO] sha1: Fixed off-by-64 bug in sha1_update

After a partial update, the done pointer is off to the right by 64 bytes.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

crypto/sha1.c

@@ -61,8 +61,8 @@ static void sha1_update(void *ctx, const u8 *data, unsigned int len)
 		u32 temp[SHA_WORKSPACE_WORDS];
 
 		if (partial) {
-			done = 64 - partial;
-			memcpy(sctx->buffer + partial, data, done);
+			done = -partial;
+			memcpy(sctx->buffer + partial, data, done + 64);
 			src = sctx->buffer;
 		}