ocfs2: small cleanup of ocfs2_request_delete()

There are two checks in there (one for inode newness, one for other mounted
nodes) which are unnecessary, so remove them. The DLM will allow the trylock
in either case without any messaging overhead.

Removing these makes ocfs2_request_delete() a one liner function, so just
move the trylock out one level into ocfs2_query_inode_wipe().

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>