GFS2: Move most of the remaining inode.c into ops_inode.c

This is in preparation to remove inode.c and rename ops_inode.c
to inode.c. Also most of the functions which were left in inode.c
relate to the creation and lookup of inodes. I'm intending to work
on consolidating some of that code, and its easier when its all in
one place.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>