ui/dbus-display1.[ch] are not properly listed in dependencies

[Michael Tokarev]

Doing a build of just a single target with --enable modules results in build
error:


 rm -rf b; cd b
 ../configure --enable-modules --target-list=x86_64-softmmu
 ninja qemu-system-x86_64

  In file included from ../ui/dbus-chardev.c:34:
 ../ui/dbus.h:34:10: fatal error: ui/dbus-display1.h: No such file or directory
    34 | #include "ui/dbus-display1.h"
       |          ^~~~~~~~~~~~~~~~~~~~
 compilation terminated.


When building without modules, or when not specifying a single target,
the build succeeded.  So I'm concluding not all deps for ui/dbus-display1.h
are specified, - dbus_ss should depend on this file I guess..

/mjt