Fix response length for Set user access command

Fixed set user access command to respond with completion code.

Unit-Test:
1. Verified the response data for Set user access command issued in
raw format and made sure that only completion code is returned.

Change-Id: Iab3ea28ddd509e2ecc76a43c80bc7068e368c43e
Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
diff --git a/user_channel/usercommands.cpp b/user_channel/usercommands.cpp
index 84e9456..f81c093 100644
--- a/user_channel/usercommands.cpp
+++ b/user_channel/usercommands.cpp
@@ -160,6 +160,7 @@
 {
     const SetUserAccessReq* req = static_cast<SetUserAccessReq*>(request);
     size_t reqLength = *dataLen;
+    *dataLen = 0;
 
     if (!(reqLength == sizeof(*req) ||
           (reqLength == (sizeof(*req) - sizeof(uint8_t) /* skip optional*/))))