gfs2: dump inode object for iopen glocks

Before this patch, glock dumps would not dump the gl_object for iopen
glocks. This information can help us debug problems related to eviction:
when AN iopen glock is blocked we can see the status of its underlying
inode and its flags, etc.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>