soc: qcom: glink_pkt: use sizeof() call as per kernel coding standards

The sizeof() specified in the kzalloc operation uses structure type
to find the size violates the kernel coding standards.

Update the sizeof() call to use pointer to structure to find the size
as per the kernel coding standards.

Change-Id: I7cea82732862b5590fa557c06303b8f0ec6357db
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>