soc: qcom: glink_smd_xprt: Clear rcid when no longer valid

Once a close ack is processed and sent to the remote, the rcid for that
channel is no longer valid.  The transport does not remove references to
the rcid which may allow the rcid to be used after it becomes invalid.

Invalidate the local copy of the rcid once it becomes invalid so that the
rcid can no longer be incorrectly used.

CRs-Fixed: 844123
Change-Id: I1a9a16fcf4d55d8fc56ee957dafb348455477f38
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>