soc: qcom: smd: Fix SMD packet sync loss issue

On remote close SMD clears the current packet size
causing the packet sync loss in SMD read opertaion.

Reset the current packet size while re-openning the SMD channel.

CRs-Fixed: 760335
Change-Id: I26c0099f280753420fd8b0bef717322f3a568895
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>