netlink_broadcast() will return -ESRCH when diagLog socket in
userspace is not present, then massive and repetitive error log
shown as below will be print. To address this, don't print
error log if netlink socket is absent.
"Ptt Socket error sending message to the app!!"
"ptt_sock_send_msg_to_app:Failed sending Msg Type [0x5050] to pid"
CRs-Fixed: 2801137
Change-Id: I14858625732c06442561e9a2e76fe2cfb6dabc12
04e2005263