utils: fixed import errors

Signed-off-by: Alessandro Comodi <acomodi@antmicro.com>

utils/bitstream.py

diff --git a/utils/bitstream.py b/utils/bitstream.py
index 36ae076..832e46d 100644
--- a/utils/bitstream.py
+++ b/utils/bitstream.py
@@ -1,6 +1,6 @@
 import json
 import os
-import util
+from utils import util
 
 # Break frames into WORD_SIZE bit words.
 WORD_SIZE_BITS = 32

utils/top_generate.mk

diff --git a/utils/top_generate.mk b/utils/top_generate.mk
index 90075d1..b28f2e7 100644
--- a/utils/top_generate.mk
+++ b/utils/top_generate.mk
@@ -5,7 +5,7 @@
 
 # Some projects have hard coded top.v, others are generated
 top.v.ok:
-	if [ -f ${FUZDIR}/top.py ] ; then python3 ${FUZDIR}/top.py >top.v; fi
+	if [ -f ${FUZDIR}/top.py ] ; then export FUZDIR=${FUZDIR} && python3 ${FUZDIR}/top.py >top.v; fi
 	touch top.v.ok
 
 vivado.ok: top.v.ok ${FUZDIR}/generate.tcl