GFS2: Get rid of dead code in inode_go_demote_ok

Function inode_go_demote_ok had some code that was only executed
if gl_holders was not empty. However, if gl_holders was not empty,
the only caller, demote_ok(), returns before inode_go_demote_ok
would ever be called. Therefore, it's dead code, so I removed it.

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