rpmsg: glink: Fix use after free in open_ack TIMEOUT case

Extra channel reference put when remote sending OPEN_ACK after timeout
causes use-after-free while handling next remote CLOSE command.

Remove extra reference put in timeout case to avoid use-after-free.

CRs-Fixed: 2303487
Change-Id: If5698ab01da266f31094d17f7aee5a8d2ef11d82
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>