selinux: sparse fix: eliminate warnings for selinuxfs

Fixes several sparse warnings for selinuxfs.c

Signed-off-by: James Morris <jmorris@namei.org>

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

diff --cc security/selinux/include/security.h
Simple merge

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