dbus: Move roam metrics to the correct interface

dbus: Move roam metrics to the correct interface

These properties were in the wpas_dbus_bss_properties array when they
should have been in the wpas_dbus_interface_properties array. Move them
to the right place. This is the logical location for these properties
and it matches both the other parts of the implementation (e.g., being
in enum wpas_dbus_prop, not in enum wpas_dbus_bss_prop) and what
was originally documented for the interface in dbus.doxygen.

Fixes: 2bbad1c7c9cb ("dbus: Export roam time, roam complete, and session length")
Fixes: 80d06d0ca9f3 ("dbus: Export BSS Transition Management status")
Signed-off-by: Matthew Wang <matthewmwang@chromium.org>