soc: qcom: glink_smd_xprt: Fake close ack in local legacy mode only

When the local side of a channel is in simulated legacy mode, the transport
must fake the close ack.  The fake close ack occurs when the remote side is
in legacy mode, however the local side can be in non-legacy mode when the
remote is in legacy mode which leads to duplicate close acks.

Make sure the close ack is only faked when it is needed due to local legacy
mode.

CRs-Fixed: 844123
Change-Id: I345f21b993eb94787a5ab9dc8bc7677d320ac708
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>