[GFS2] Remove unused code from glock layer

Remove the unused sync feature from glocks. This is currently done by
calling the required functions to sync pages/blocks directly so this
code isn't needed.

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

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

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

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

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