cmd_utils - Import PIPE to this namespace

So users don't need to import subprocess again just for PIPE.

TEST=Run related tests on link
BUG=None

Change-Id: Id891dda00eb0c6d208d7390b1bb6534a61374b12
Reviewed-on: https://chromium-review.googlesource.com/180392
Reviewed-by: Hsinyu Chao <hychao@chromium.org>
Commit-Queue: Owen Lin <owenlin@chromium.org>
Tested-by: Owen Lin <owenlin@chromium.org>
diff --git a/client/cros/audio/cras_utils.py b/client/cros/audio/cras_utils.py
index a47a058..54a4f13 100644
--- a/client/cros/audio/cras_utils.py
+++ b/client/cros/audio/cras_utils.py
@@ -4,7 +4,6 @@
 
 import logging
 import re
-import subprocess
 
 from autotest_lib.client.bin import utils
 from autotest_lib.client.cros.audio import cmd_utils
@@ -112,7 +111,7 @@
 def dump_server_info():
     """Gets the CRAS's server information."""
     args = [_CRAS_TEST_CLIENT, '--dump_server_info']
-    return cmd_utils.execute(args, stdout=subprocess.PIPE)
+    return cmd_utils.execute(args, stdout=cmd_utils.PIPE)
 
 def get_selected_nodes():
     """Returns the pair of active output node and input node."""