xfrm: Zero padding when dumping algos and encap

In the Linux kernel, the following vulnerability has been resolved:

xfrm: Zero padding when dumping algos and encap

When copying data to user-space we should ensure that only valid data is copied over. Padding in structures may be filled with random (possibly sensitve) data and should never be given directly to user-space.

This patch fixes the copying of xfrm algorithms and the encap template in xfrm_user so that padding is zeroed.