GFS2: Move gfs2_unlink_ok into ops_inode.c

Another function which is only called from one ops_inode.c so
we move it and make it static.

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

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

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

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