autofs: comment on selinux changes needed for module autoload

Due to the autofs4 module using a file system type name of autofs
different from the module containing directory name autoload did not
function properly.  To work around this kernel configurations have often
elected to build the module into the kernel.

This can result in selinux policies that prohibit autoloading of the
autofs module which need to be changed.

Add a comment about this to "possible changes" section of the autofs4
module help.

Link: http://lkml.kernel.org/r/152686474171.6155.1239659539983577463.stgit@pluto.themaw.net


Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>