soc: qcom: glink_probe: Use ref count for holding ssr context

During ssr rpmsg ssr device will unregister, which can result
in use of stale device pointer in ssr callback function.

Now incrementing refcount inside ssr callback function to
prevent release of rpmsg device.

CRs-Fixed: 2551255
Change-Id: If3fc57c4635378dc6fdcb7df120c83dca0e83758
Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>