Fix: fd-tracker: dereference of lttng_inode after NULL check

handle->inode is checked for NULL but used unconditionaly
on line 873 (lttng_inode_put).

1407756 Dereference after null check
Either the check against null is unnecessary, or there may be a null pointer dereference.
In fs_handle_close: Pointer is checked against null but then dereferenced anyway (CWE-476)

Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>