packDev_t: Clear out uninitialized memory garbage

If pDev is NULL (i.e. not found in associated devices list), only the first
2 bytes of the buffer (shortAddr) were filled (with INVALID_NODE_ADDR).
All the remaining buffer contained uninitialized memory garbage.
Hence the memset, to zero out the entire buffer beforehand.

See Koenkk/zigbee2mqtt#13478 (comment)

@slugzero

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

source/ti/zstack/mt/mt_util.c

@@ -1525,6 +1525,8 @@ static void MT_UtilBindAddEntry(uint8_t *pBuf)
  ***************************************************************************************************/
 static void packDev_t(uint8_t *pBuf, associated_devices_t *pDev)
 {
+  memset(pBuf, 0, sizeof(associated_devices_t));
+
   if (NULL == pDev)
   {
     uint16_t rtrn = INVALID_NODE_ADDR;