Fix error message on chunked insufficient bytes

Failure to read the right number of bytes (typically due to remote HUP)
would log "straight insufficient bytes", which is the same as we log for
C-L based fetches. Change this to "chunked insufficient bytes". (Assuming
this was a copy-paste error).

bin/varnishd/http1/cache_http1_vfp.c

@@ -161,7 +161,7 @@ v1f_pull_chunked(struct vfp_ctx *vc, struct vfp_entry *vfe, void *ptr,
 			l = vfe->priv2;
 		lr = v1f_read(vc, htc, ptr, l);
 		if (lr <= 0)
-			return (VFP_Error(vc, "straight insufficient bytes"));
+			return (VFP_Error(vc, "chunked insufficient bytes"));
 		*lp = lr;
 		vfe->priv2 -= lr;
 		if (vfe->priv2 == 0)