netmgrd: Allow to kill processes which are non responsive

If netmgrd is waiting on a process to complete for more that 2 seconds,
it tries to kill it to continue execution rather than being blocked on
it forever. Fix this denial observed during that operation -

W/netmgrd ( 1445): type=1400 audit(0.0:69838): avc: denied { sigkill }
for scontext=u:r:netmgrd:s0 tcontext=u:r:netutils_wrapper:s0 tclass=process
permissive=0 ppid=1 pcomm="init" pgid=1445 pgcomm="netmgrd"

CRs-Fixed: 2098339
Change-Id: Ibd032f73edb90d93dd10c2664f414717c1b1aa4d