lzo: Update dst_len even on error

This allows the caller to easily detect how much of the destination buffer
has been used.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/lzo/lzo1x_decompress.c b/lib/lzo/lzo1x_decompress.c
index 35f3793..ebdf10b 100644
--- a/lib/lzo/lzo1x_decompress.c
+++ b/lib/lzo/lzo1x_decompress.c
@@ -102,8 +102,10 @@
 		tmp = dlen;
 		r = lzo1x_decompress_safe((u8 *) src, slen, dst, &tmp);
 
-		if (r != LZO_E_OK)
+		if (r != LZO_E_OK) {
+			*dst_len = dst - start;
 			return r;
+		}
 
 		if (dlen != tmp)
 			return LZO_E_ERROR;