meson: add the prefix to the dbus dir
meson: add the prefix to the dbus dir

Otherwise where the directory is used within meson.build, the prefix would be
missing. No real effect since we don't use it anywhere but let's be safe.

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

whot/libratbag,whot/libratbag,libratbag/libratbag,libratbag/libratbag,libratbag/libratbag,whot/libratbag