selinux: remove unused variabled in the netport, netnode, and netif caches

This patch removes the unused return code variable in the netport,
netnode, and netif initialization functions.

Reported-by: fengguang.wu@intel.com
Signed-off-by: Paul Moore <pmoore@redhat.com>

diff --cc security/selinux/netif.c
Simple merge

diff --cc security/selinux/netnode.c
Simple merge

diff --cc security/selinux/netport.c
Simple merge