soc: qcom: hab: fix the leak risk in hab_vchan_get

When getting a vchan after receiving a message, it has probability that
this vchan is closed concurrently. So when refcount is increased by
kref_get_unless_zero, but flag vchan->otherend_closed or vchan->closed
is true at this time, it will return vchan as NULL, and the hab_vchan_put
will not be called in hab_msg_rev. So adjust the timing here can avoid the
leak risk.

Change-Id: If78c1c41bc4fd05b3288c0324bb9e0aed8493c5f
Signed-off-by: Yao Jiang <yaojia@codeaurora.org>