[GFS2] Style changes in ops_address.c

As per the remainder of Jan Engelhardt's fourth email comments,
remove an cast thats not required. Also tidy up the "limit" code
in stuck_releasepage().

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>