homed: fix home_unlocking_finish reporting success as failure

homed: fix home_unlocking_finish reporting success as failure

In home_unlocking_finish(), the success path calls operation_result_unref()
with the local variable r and the uninitialized error object. If either
user_record_good_authentication() or home_save_record() fails (both are
logged as "ignoring"), r is left negative and the D-Bus caller receives
an error reply despite the home having been unlocked successfully.

This causes PAM to reject the session even though the home directory is
mounted and accessible.

Fix by passing 0 and NULL — consistent with every other success path in
the file (home_locking_finish(), home_activation_finish(), etc.).

Signed-off-by: dongshengyuan <dongshengyuan@uniontech.com>