the nvmeof gateway requires privileged containers with
sys_admin capability. the rook-ceph scc only allowed mknod,
causing pod creation to fail on openshift with:
"unable to validate against any security context constraint"
add sys_admin to allowedcapabilities in the helm chart sccs
and the go scc helper. this does not affect other daemons
(osd, rgw, mgr, mon) since they do not request sys_admin.
the operator-openshift.yaml example already includes
sys_admin, so this aligns the helm charts to match.
Signed-off-by: Oded Viner <oviner@redhat.com>