[GFS2] More code style updates

As per Jan Engelhardt's fifth email. This has most of the changes
recommended, which is the removal of casts which are not required,
some indenting fixes and similar.

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

diff --cc fs/gfs2/ops_file.c
Simple merge

diff --cc fs/gfs2/ops_fstype.c
Simple merge

diff --cc fs/gfs2/ops_inode.c
Simple merge