net: memset smsg to avoid the padding data

memset smsg to avoid the padding data of kernel to be shared
with user space. Fix is to set fields event to all "0", but there is
actually 6 bytes padding between "sktype" and "skflags", so memset was
done to set all the padding bits to 0.

CRs-Fixed: 2287852

Change-Id: I435486b80ad19c5fa54b098680623e7a4f080198
Signed-off-by: Kaustubh Pandey <kapandey@codeaurora.org>
Acked-by: Chinmay Agarwal <chinagar@qti.qualcomm.com>