GFS2: eliminate log elements and simplify

This patch eliminates the gfs2_log_element data structure and
rolls its two components into the gfs2_bufdata. This makes the code
easier to understand and makes it easier to migrate to a rbtree
to keep the list sorted.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

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

diff --cc fs/gfs2/incore.h
Simple merge

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

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

diff --cc fs/gfs2/lops.h
Simple merge

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

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