seemp: adjust interpretation of rooting report

In the newer versions of EL2 rooting report, a pointer to task_struct
will be supplied as the actor. Extract the pid from the task_struct
and log the pid.

Change-Id: Ic38d0feb8d433f02e614f5e578f21dc12a9d5f38
Signed-off-by: Yida Wang <yidaw@codeaurora.org>