Linux upstream kernel Overlay file systems support SELinux

Remove checks that prevent overlay and SELinux from working together.
Fixes are arriving in the 4.9 kernel.

Signed-off-by: Dan Walsh <dwalsh@redhat.com>

man/dockerd.8.md

@@ -235,7 +235,7 @@ output otherwise.
   Force the Docker runtime to use a specific storage driver.
 
 **--selinux-enabled**=*true*|*false*
-  Enable selinux support. Default is false. SELinux does not presently support either of the overlay storage drivers.
+  Enable selinux support. Default is false.
 
 **--storage-opt**=[]
   Set storage driver options. See STORAGE DRIVER OPTIONS.