efirtc: explicitly set llseek to no_llseek

Now that we've removed the BKL here, let's explicitly set llseek to
no_llseek since the default llseek is not used here.

The default_llseek function still contains the BKL.  When we are auditing
code to see if we can remove the BKL, this is one of the hidden
considerations we need to take into account.  i.e., is there
syncronization between code that has the BKL and llseek.

At the same time we remove the BKL it would be a good idea to do indicate
when no llseek function is required, so we don't have to revisit this code
again, when we are trying to determine if we can remove the BKL from the
default_llseek.

Signed-off-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>