selinux: Drop needless getfilecon()-s

selinux: Drop needless getfilecon()-s

When SELinux support was first introduced the libselinux library
wasn't that advanced and setfilecon_raw() or fsetfilecon_raw()
could fail even when the target context was set. Looking at the
current code [1][2] this is no longer the case. We can drop our
workarounds.

1: https://github.com/SELinuxProject/selinux/blob/master/libselinux/src/setfilecon.c#L10
2: https://github.com/SELinuxProject/selinux/blob/master/libselinux/src/fsetfilecon.c#L10

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>