IMA: drop the inode opencount since it isn't needed for operation

The opencount was used to help debugging to make sure that everything
which created a struct file also correctly made the IMA calls.  Since we
moved all of that into the VFS this isn't as necessary.  We should be
able to get the same amount of debugging out of just the reader and
write count.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>