soc: qcom: glink_pkt: Add multiple client support

In some cases, one client opens the glink channel and performs the data
exchange and other client opens the same channel to check TIOCM signal
state.

Support multiple clients to open a glink packet device by increasing
reference count to device.

Change-Id: Ifd5cc791d9e9feddab6e9b304909438285a4ad79
Signed-off-by: Arun Kumar Neelakantam <aneelaka@codeaurora.org>
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>