soc: qcom: glink: Change dummy xprt allocation to kzalloc

Change allocation from kmalloc to kzalloc to prevent any usage
of function pointers that are not initialized.

CRs-Fixed: 2065710
Change-Id: I3a7589158e799e19072ca6a6847986b99da5d9ab
Signed-off-by: Chris Lew <clew@codeaurora.org>